I have a black Australian mastiff he won't eat and when he drinks water he vomits it back up, I gave him a penicillin shot but I'm still worried I haven't been able to get him to eat anything, and he's weak

Has he seen a Vet? Dogs dehydrate very, very quickly. I'm guessing - and only guessing - that he has some type of infection, therefore needs penicillin - ?

If he's weak he needs to see a Vet. No dog willingly starves itself to death.

Why did you give him a penecilian shot? Penecilian is for infections.. not vomiting. I hope he has no allergies to the drug and I also HOPE you gave the correct dosage for his body weight.

If he is vomiting, but is still drinking, give him water that matters.. Give him pedialyte or gateroaid to help him keep hydrated and keep his electorlytes up. As for the vomiting itself, sometimes these things need to run their course. Try to remember if he got into anything that would cause a blockage. Feel his stomach, is it kind of hard and distended? Or is it soft? Does he look bloated? Or normal?

Like I said, vomiting can either be a minor problem or it can be something very serious. Monitor your dog for the next 24 hours. Don't give him his regular meal, feed him small amounts throughout the day with you watching him carfully. When feeding him, give him a very mild diet of browned hamburger and rice or boiled chicken and rice.

If he continues to eat and throw up and throw up water and looks miserable, then its time for the vet.

And I was advised to brown the hamburger and then rinse it in water to make sure ALL the fat is removed. I figure it tastes like cardboard but the dogs eat it.

A dog that is induced to vomit when it drinks water has something amiss that needs investigated rather than allowed to wait and see what happens. Unless, possibly, this is something that has just started within the last few hours. If it has already been happening 24 or more hours, then there is no benefit to waiting another day, unless it has been determined what the problem is NOT.
More water, regardless of it's contents or it's value, is most likely to cause him to vomit that as well.

A full blown case of inflamed stomach (gastritis) will make vomiting likely after anything stimulates the stomach, which in turn stimulates the pancreas. And serious pancreatitis, in turn, stimulates vomiting, if not more. Severe pancreatitis can be instrumental in the death of the animal.

Without knowing how old this dog is, we can't rule anything out. So, I'll add a possible cancer or full blown ulcer as other possibilities. Could he have gotten something caustic(acidic) and swallowed it? Does he have free access to go as he pleases outdoors? Are there any people locally who would put out dangerous temptations for him to eat? (Well, we know the answer to that. Question should be, are there any around you?) The list of possibilities is almost endless.

He could easily be weak from whatever is causing him to be nauseated. As for lack of food, how long has he been vomiting? It takes quite a while for a dog to starve, and if he is that hungry, he would eat anything. If not, then there is, most likely, some significant problem that should be discovered and treated. Until then, my advice is offer nothing solid to the dog, until he, hopefully, sees a vet and has it determined what is the problem, or pending that, he should stop vomiting. And yes, vomiting can dehydrate the dog, which is another indication for securing a vet exam as soon as possible.

Again, anything that stimulates vomiting is not beneficial. Try ice chips in small amounts instead of liquid. And get that vet visit and exam!
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He is 7 months 2 8 months

I can get him to drink water but after a few min he vomits I gave him a penicillin shot to help out if its any sickness as far as a virus that mas cause it, I was afraid to use promethizine to counter act the vomiting but due to the shot I was worried that it may put him in a worse state so I used THC to help counter act the vomiting it worked so far he has drink water and has held it down but getting him to eat is diff I put food in front of him he avoids it

TAKE HIM TO A VET BEFORE HE DIES BEFORE YOUR EYES!

Do you also self medicate yourself?

Really? How long will this go on before you take this dog to a vet? He's going to die if you don't do the right thing. Why is it that you need us to tell you to take him to get real help? And... even after it has already been stated, you're still here trying to treat the dog yourself.

People that can't or won't properly care for an animal shouldn't have one... plain and simple.

Take him to the vet before he dies!

Why when 85% of parvo cases are fetal cause of the medicine and most vets can't properly treat an animal when they won't allow the animal being seen to enter the vets office cause of infection and they allow only 1 person to see and handle the medical attention, home remedies work more better and healthier than vet medicine so the person who says ''People that can't or won't properly care for an animal shouldn't have one... plain and simple'' the most proper care kills when it comes to parvo, parvo simply put becomes deadly cause of the immune system and lack of nutrition to fight it other than that its like a cold its got to make its way threw and pass cause parvo is like the common cold there's no cure for the simple fact as each year pass a new DNA altered strand of the parvo virus is passed on from other animals caring the inert virus till it finds a desirable host, after introduction to the host it multiples and then attacks

Jake, you have been given the best advice we can give. If you won't take your dog to the vet, none of us are going to offer any further advice, simply put, because we can not, and NONE of us here will take responsibility for the death of your dog. We wish you well, and I hope your dog makes a speedy recovery.

I have to ask, how is he doing now?