40 Male 5’7 119kg UK

Since my surgery almost three weeks ago Ive been on prednisolone. In hospital I was fine with injections, but the day after I went home after five days in hospital, i developed itching skin on my ankle and its spred to my whole body. My body is like a giant wound all over from ankle, to chest to even buttocks and groin. Its everywhere. doctors arent sure if it is the prednisolone which caused it but its the only thing different i am taking. Never had any allergies before. Had to go to a and e yesterday and they have decided to swap it for another cortisteroid, hydrocortisone, from tomorrow since I cant just stop steroids yet.

Im terrified it wont go away because creams and strong pills havent worked. Im really hoping it is pred causing it and it might flush out of my system and be ok. Does anyone know , if it is prednisolone causing it, how long after i swap or stop should I hopefully be back to normal?

Im desperate, its been driving me insane for two weeks. My gp gave me cream and antihistimines but neither has worked and yesterday they refered me to a and e. They did blood work and that was all fine and they arent sure whats causing my reaction. I really dont know what to do, im going insane .