My Iphone 5s camera is broke

Okay so recently my camera on my iphone has been just a black screen, nothings covering it, its just black and when i try to switch cameras the app freezes. Its been like this for a month and its very on and off. Sometimes the camera is fully working, and the next minute it is black again. And also when the camera is working the little focus box doesn't work and the pictures come out blurry. Also my brightness on my Iphone is weird too, it sometimes just randomly gets dark. Please tell me how to fix it, i can't spend a lot of money on this, also please leave names of cheap companies that can fix this, Thank you.

This would only happen if you dropped it, of course you aren't willing to say that in your post…

My camera is black, can't see anything… How do I fix?