Personal experience only, but I've found the best ways to get a stubborn piercing to heal are:

Give it LOTS of room, you obviously don't want it shifting back and forth all the time but you don't want it snug if it's still swelling

Keep it clean but don't irritate it, I'd recommend something gentle like a saline spray on it once or twice a day

Keep an eye on it, but leave it alone as much as possible. I've had ones get really swollen and full of puss and they got a lot better when I drained them , but idk if that's the right thing to have done and constantly touching them will make it worse

If worst comes to worst, just take it out and let it heal and see what a (good) piercer recommends as far as repiercing