help me now

I had gallbladder surgery a week ago today and have broken out in a rash/hives all over my body. I first noticed the rash on Monday and now it's Saturday and it just keeps spreading. I've been to the ER twice and they gave me steroids and anti histamines to help. Unfortunately it's still getting worse. They surgeon thinks it was caused by Percocet so I stopped taking that and its still spreading. I also have recently started using vinegar as a cleaner for everything and am wondering if that could have anything to do with this since my hands are effected the worst. Last month I also switched pharmacies and am taking a different generic medication than before. Could that be what it is? I just don't get why it could be those things when it's been a whole month of these changes and the rash/hives started after my surgery. Did I weaken my immune system? My surgeon wants me to go back to the ER, but I've gone twice and they still haven't figured it out. Also, I read about how bad the side effects from steroids can be so I'm not sure I want them pumping me with more of them through an IV. Has anyone ever experienced something like this? I'm so at a loss for what to do. My whole body itches horribly and my hands are swollen and are actually hurting from this.