Itchy rashes on inner thigh and scrotum may be due to increased sweating which will lead to many fungal infections. Increased itching during night involving scrotal region ,needs proper evaluation, whether its present in fellow mates if you are staying in hostel or paying guest home, Avoid tight jeans do rinse your clothes thoroughly and dry your clothes under sun light . Use less of detergents Pls dont apply creams given by medical store. Consult proper dermatologist for proper treatment. If u apply any medication without proper advice it will be much worse for u and next treating dermatologist.