My pup is 3 months old. She ate a lot since she was with me. I de wormed her last month and there was few worm out. Last few days I de wormed her again half of the tablet she took last month. After 1 one day she feel ill already and vomiting a little water like only a saliva and she never eat anything at all. Seems her stomach is aching. Wanted to vomit but she can't. What will I do to this?

Go see a vet.

Please contact your vet. It could be a lot of different things... Sounds like she could be having a reaction to the wormer. You might want to brown hamburger and mix it with rice...

I agree with going to the vet.
It could be due to the worming tablet (what type did you give?)
Or a completely different reason.

See if she does exercise and get ungry after you find out why she can't eat

see if she does exercise and get ungry after you find out why she can't eat

It's a PUPPY!! Geez...

ITS A PUPPY!!!!! Geez....

Indeed, at 3 months no puppy should be being exercised hard (nothing more than playing and short walks) and larger breeds shouldn't undertake hard exercise until 1 year of age.

Of a dog won't eat, it's a good sign that something is wrong. Dogs have survival embeded into their brains.
I agree with Shaz and Lucky, not thebest idea to exert your pup.
Has you puppy been vaccinated yet?