Itchy on the body particularly scrotum

Hi

I have this itching problem ever since I came back from Japan in February. My body would itch around my back, legs arms, buttocks and ball sack. There is no rash or anything like that. When i scratch it for a while it will go red and there will be enraised bumps in the area i scratched. This was bad in the first couple of months where i would be itching on say my leg and i would scratch it and the whole area would become bumpy skin. This will go away after i stop scratching. This has settled but I still get scratching urges where I have to scratch those particlarly parts of the body. However my scrotum has never settled. I always have to scratch it several times a day and it gets very itchy. No rash, my ball sack does not get red or anytihng like that. There are also white enraised bumps on my scrotum. i scratch and it usually goes away. I dont get whats the problem!!! There is no lasting effect it only happens from time to time during the day. Please help!!