How to find out what my friend is allergic to on me?

Heads up, im emotional after being told all this plus some an hour ago.

My friend, I will call Stevie, is having allergic reactions around me. This is making my friends/roommates upset that they can't have them over. They even asked me to not really keep stuff in common areas because of it. I only know of it happening at an event we go to with me, but I guess its everytime.

The issue with getting a test is that they cannot afford it, and they live 10 hour drive one way from the rest of us. So we can't really test.

What we know: -this has only happened when coming into contact with me/my stuff. Idk if i touch something if it does it. -it causes itching where I touch I use the same detergents as my roommates, and we all use similar body wash (usually similar brands and/or scent) -when I am not there, not even my roommates trigger it. Only my items. The first time was about a year ago, ive known them for longer (at least 5 years before)

Idk what to do. Im tempted just to move out, after having other things blamed on me, but I dont wanna lose all my friends over this. What could this be? How can I test? If its me, can I do anything? Thank you.