Vet said everything's finewith the kitten. But he sneezes 3 times a day and scratches/licks behind e

He's 8 weeks old. After adopting him from the shelter i went to the vet and he said everything was fine with him and that he doesn't have flea.The next day i took the kitten to the vet again for his sneezes and vet said sneezing was normal (he had sneezed twice that day) but i asked for antibiotics (liquid form) anyway. Today he sneezed 3 times while i was watching him. i don't know how many times he sneezed when i was not in the room.

Also, since yesterday i have noticed him scratching/licking behind his ears/armpits/back/tummy

I got him from the shelter. He could have flea but i am not sure what i should do.

Kitten doesn't have watery eyes, nasal discharge, or anything like that. He's playing fine and eating fine too.

He has another vet appointment in 21 days for his second vaccine

Did you get the antibiotics to treat him for the sneezing? It probably isn't anything. Cats sneeze. But it could be the beginning stages of a URI. Even if you don't have antibiotics now you can wait to see if it gets better as many of these are cleared up really fast just by a cat's immune system.

I don't know a cat that doesn't regularly scratch and lick even if they have no fleas. If you see evidence of fleas, actual fleas leaping off the cat or flea dust when you brush the cat then there are fleas. If this is the case wash he kitten with dawn dish soap to get rid of them and vacuum/wash things that the kitten has been around. At 8 weeks a kitten is too young for any kind of flea medication. 

That was very helpful. Thank you. (Good news, i haven't seen any fleas or flea dust yet....but i am giving the antibiotics anyway. I hope whatever it is, the kitten immune system can clear it asap.)

If it is the beginning of a URI the antibiotics should make it easy to get rid of fast. When our kitten had one (full blown, coughing, discharge, sneezing) she was feeling better and it was almost gone a few days later. Of course, once you start a course of antibiotics make sure that you finish it! Otherwise you just build more resistant strains of what you're fighting.