I know how frustrating it can be. I just got over an allergic reaction to Imodium AD. It was real frightening. I broke out in red welts and hives all over my body. My lip started to swell. I am sure my throat was next. I drove quickly to the doc and they gave me a steroid shot and benadryl. It has been a week now and i just not got all the reaction out of my body. It was horrible. I never knew I was allergic to that. It can come on so sudden. I hope you can get to the bottom of what is cause your hives and allergic reaction. Make a doctor test you for anything you can think of. I would demand it. Good luck!