Weird skin redness under breasts (no pic)

Hey everyone. So for the longest time I've had a problem with the skin under my breasts. It turns red and blotchy and super itchy, often. I always thought it was because I was sweating but recently its itchy and red even right after a shower. My doctor said it was probably a yeast infection but the cream he told me to use isnt helping at all. Should I be concerned??