i have this read rash on my neck and it seems to be spreading down the sides of my neck (it started in the back near the hairline.)

its super itchy an burns occasionally..the doctor perscribed a cream to me atleast a year ago, but it didnt really work. i put ozinol on it and it seemed to have gone down. but:

1. should i see the doctor again?
2. could it be caused by sweat and heat?

plz help its really bothering me.

p.s im 17. so i dont know all that much about medical stuff..