What is this rash due to?

Not enough info: There are many types of rashes with many causes. There is not enough information to venture a guess.

Rash: Hi, it’s hard to say without a picture but there is a great app that may be able to help you get a diagnosis without being seen in person by a dermatologist. The app is called VisualDX and is one of the best, if not the best out there. Many clinicians, including myself, use it. Just snap a photo and it gives you a list of possible diagnoses. Good luck!