Burning Pain While Walking - Need Help!

Hi! I’m a 20 yr old woman with crohn’s and celiac. Whenever I go on walks (typically outside, but it can happen inside too) i get really horrific burning pain- I’m talking walking down the street to get the mail and breaking out into hives… from just WALKING. I have to run home in pain and pull my pants down to scratch it because it’s burning so bad. It happens in public too and it’s horrible. It’s been happening for years and I’ve seen every kind of skin/autoimmune doctor you can about it and nobody knows what’s wrong. It’s horrible because I’ve been unable to go on walks for years and it makes living so hard. It doesn’t matter what pants I’m wearing (long or short, any fabric), I’ve tried everything!!!! I have a lot of random skin problems (possible psoriasis from crohn’s, I also get severe burning pain on my cheeks and knuckles when my body gets warm) but no doctors have been able to identify what any of them are. Does anyone else deal with this???