What is wrong with my puppy?? Itching problem??? Please give advice.?

Okay, so I have a German Shepherd pup hes about 6-8 months old, we got him around February when he was 4 months, hes been to the vet once for puppy shots, and another because he ate socks and been throwing them up but he stopped throwing up once the vet gave him medicine. He hasn't been to the vet in about 3 months and he has had this REALLY bad itching problem kinda by where his "thing" is, its very red like somethings wrong, bumpy big zits, scaly, and dry. He cries a lot and I think its because of it but I'm not sure if German Shepherds cry all the time or what. He bites at it and itches it at least every 3 minutes he chews on it very hard and his balls itch too. I don't think he has any fleas I have checked him a few times and theres no signs but he does itch a lot everywhere else too. He eats weird things like stuffed animal eyes and noses, socks, buttons, 1 tiny screw (attached to the stuffed animals eye) anything he can find that looks like something he can eat. I don't give him the toys he just takes them randomly out of my and everyones room. He does have toys but does not play with them very much he likes to play with stuff thats not his. I know its not healthy but by the time I catch him eating it he has already swallowed it, like today he ate a nose, and eyes off of a stuff animal and screws that were attached to the eyes. Whats happening to him?? Can it be because hes been eating that stuff??? He eats three times a day two cups and fresh water everyday. We just moved (we have rocks in our backyard, grass in the front) and it seems like it has gotten worse, I know animals can only get fleas from grass. I don't think there are any fleas here I haven't felt any biting on me or anything. He still acts normal he still plays and eats but he always itches and bites at that area. Can it be an allergic reaction?? Or what??? Please let me know it will mean so much. Thank you.