I promise, this WILL end! We went through this with Jake, and it ended almost as fast as it started. We tried a few different things that worked. Everytime he would bite, I would yelp just like puppies do when they are hurt. That would get his attention and he would stop and stare at me. I would tell him "no bite". I wouldn't yell or even raise my voice, but I would say it sternly. I would also give him something he was allowed to chew on, like a toy or chewie. If this doesn't stop him, put him down and ignore him for a few minutes. They don't like being ignored.
He would try to bite our feet and toes while we were walking, so I sprayed some "Bitter Apple" on my socks. That stopped him dead in his tracks, and he stopped trying to bite our feet. If he even saw the spray bottle, he would stop what he was doing.
Now I have Jackson and he's at the biting stage. So far, the yelping is working. He will stop, I'll give him a chewie, and he will happily sit on my lap and chew on it.
The most important thing is to be consistent and don't give in. They learn by repetition, so you have to keep telling them "no" until they understand what no means. Jackson knows what no means, but of course, he's a puppy so he forgets. Once he is reminded, he listens really well.
There are times when Jackson and Jake are playing, and Jackson will bite too hard. Jake will let him know, and he backs off.
Good luck, I know it can be frustrating!