Desperate need of advice!!

Hi everyone, my son has had this rash for a really long time, I have taken him to doctors, allergist, I have an upcoming appointment again for someone to take a look at it but I really wanted to see if anyone else has seen this? It gets red, almost like it burns, always in the same spot. The allergist prescribed hydrocortisone 2.5% and use it almost everyday, but I’ve read it thins the skin so I’m scared to keep using it. I’m not sure what to put on it and now it seems to leak clear liquid not thick as pus tho. Any info or advice will be appreciated I don’t know what to do. I avoid foods he’s allergic to and clothes that irritate him.