Hi I'm a first time dog owner,my dog is about 7 months old and I gave him his deworming formula last month.but I've noticed that in the last couple of days he has puked about 4 times,it's a yellowish fluid. I was just wondering if that could be his system clearing out or that maybe he really is sick?

He could have had a bad reaction to the working formula but I doubt it, if it has taken a month for symptoms to show it's more likely unrelated. It could just be an upset tummy which puppies get a lot but you should go to the vet just to be sure it's not more serious.

Has he been eating grass? They do this to make themselves bring up an excess of digestive juices in their stomachs. My dogs occasionally bring up this yellow fluid (sometimes a few times in one day). I've never worried about it and its never turned out that they are unwell. I believe its, like when they eat grass, getting rid of too much digestive juices in their tums. If there are any other syptoms or if it persists, its probably worth checking it out with the vet though.