Diaper rash at butt cheek fold

How did u get your lo rash to subside?? My 7mo bb having quite bad diaper rash at butt hole and we figure it's due to her pooing 2-3 times a day as she's on solids now and full formula feed, previously was ebm. Seen pd twice and he gave antifungal cream and a stronger steroid when it came back. But now seems to not get better and became red and inflammed. She cries out in pain whenever she poo and we change her. Now I change her diaper every 2-3h and use the creams and desitin but not much improvement. Help!