@simrin-- I'm sorry to hear that but you know, those kind of serious side effects of doxyxycline hyclate is not that common. Most people don't experience much side effects. I've also taken it several times for various bacterial infections and at most experienced headache or maybe fatigue. It was nothing serious and I finished my course without problems.
Allergic reactions can happen with every drug and everyone responds differently to medications. This doesn't mean that it will cause the same side effects in everyone.
I think that doxycycline is overall a safe drug.