I had an ingrown toenail on my left big toe that developed from an accident I had as a kid, big rock fell on my foot. A couple of years ago, I had a foot doctor take care of it. He cut off the extra nail and killed the problem roots with acid or something. There haven’t been any problems since.
This is probably the best method, and the method with the least amount of pain. I got a couple of needles in my toe, but it was nothing. And I couldn’t feel anything but uncomfortable pressure while he ripped things out and jammed acid-coated-cuetips up my nail bed. By the time the numbing wore off, a little whiskey took care of any pain. I was on my feet in three days.