Below scrotum and toward right leg i have a damp red rash that smells like fish. if scrubbed in shower produces slight pains. what is this?

Fungal infection: Candidal ( fungal) rash. Metronidazole or Nystatin topical (over the conter).

Possible fungal: The damp red rash with a fishy smell may be from a longstanding fungal infection; however if sexually active, could be related to std. I would recommend over the counter antifingal cream ( lotrimin (clotrimazole) af) - apply a thin layer am/pm for 5 days- if not resolved- see your pohysician and get checked for stds.