It’s just how it is. Doctors never tell you that antibiotics hurt your immune system, though. It makes them seem a lot worse than they are. They do help in the long run if you’re not allergic to them.
Your problem sounds like a mild allergic reaction, because the worst most people get is just feeling like shit, and maybe a cold that takes them out of commission for a few days. Just make sure your doctors know you can’t take those anymore and don’t withhold symptoms from them. That makes it worse because they can’t help you with something they don’t know is wrong and they can’t give you alternatives based on reactions they don’t know your body’s having.
It may seem like the doctors simply don’t know what they’re doing, but they probably went in pretty blind and gave you something nobody knew you were allergic to. As bad as it sounds, the medical field can be a bit of trial and error.
Also, if you’re ever feeling up to it, I’d suggest looking into an allergy test to see what you are and aren’t allergic to. Should just be able to ask your doctor about it when you see him. It’s not necessary by any means, but maybe it’s not a bad idea if you had that kind of reaction to something.