Allergic to all antibiotics. Why is my body doing this?

I am 61 years old and I started with a penicillin allergy when I was about 25 or 26 as the years have gone by I've become allergic to more and more antibiotics to the point where there is nothing that I can take that I'm not allergic to I have had anaphylactic shock rash hives difficulty breathing you name it I've had it. Now I have had a dental infection for 5 years and I am sick now with what could be pneumonia and no doctor will treat me. I have gone to the emergency room and they told me I was lying and it was my anxiety and if I didn't take this medication they were going to put me in a mental hospital. So now I'm also afraid to go to the emergency room because of the way they treat me I don't know what to do I've tried everything and it's so difficult because no one believes you even though they can see the rash or whatever the reaction is they claim it's my anxiety. I am searching for a doctor near me who can figure this out but unfortunately I have Medicaid insurance and I have been told that that is never going to happen. So apparently it's like this one nurse said to me when I was at the emergency room she said the only good Medicaid patient was a dead one so she said that the doctor did not care what happened to me and to go home and best of luck. I I am so frustrated and Afraid because I don't want to die and I never asked for this and I don't know what's happening and why my body is doing this and this horrible attitude of the medical profession is only making things worse. I hope I find an answer to this soon.