help with roundworms and FeLV

My kitty tested positive for FeLV and now has roundworms. the vet gave us a medicine to cure the worms. its basically just 2 pills. 1 taken already and then they said give him the last after 3 weeks. will this pill start killing the worms right away and when should he start getting better?

He does walk like hes "drunk" (his back legs arent functioning correctly), is its the worms doing this? or is it cause of his leukimia? he has started to eat and drink on his own now(before he wouldnt and we had to force feed him). although he likes to just lay under the bed all day and will only come out to eat/drink/use litter box.

How old is your kitty?

Hes about 1 yr old. And he actually will only drink on his own, he wont eat(my sister feeds him). And he has problems going #2.

The vets wont help much because he has FeLV and thinks that he should be put to sleep... but I am hoping he gets better. I really dont want that.

The 2 vets over here just are horrible... one only cares about money and the other seems like they graduated vet school way too early...