lmk if i’m just overthinking this

My almost 5 month old has been having this problem for about 3 months now. Her peds doc gave me hydrocortisone cream to put on. I’ve been putting it on twice a day and once it’s gone I stop because I don’t want to use a steroid cream like that too much. She’s on Kendamil Whole Milk but idk if she’s having cmpa reaction or it’s something else.