My 3.5 mo old pit bull puppy has been itchy since we got him at 7 weeks. He just cries and itches all the time. The vet said gie him benadryl and oatmeal bathes. According to vet he's too young for a flea allergy as of yet but I'm not so sure. His father had the same prob, and ended up scratching himself half naked. I've been trying everything and nothing is helping for more than a few hours. He's so miserable I can't stand it. What can I do?

You misunderstood the vet! A newborn can suffer horribly from fleas. Flea 'allergy?' Flea BITES! Get him some monthly drops like Frontline or Advantage from the vet NOW!

Or find another vet. This is just too much.

Sounds like allergies to me. What are you feeding him?

Along with the probability of allergies, another thing to consider would be parasites, not only fleas but mites or lice. Has your vet done a skin scrape to check for this.
Benadryl and oatmeal shampoos are only going to provide temporary relief, the problem needs to be discovered in order to properly treat.