After taking such a long break your forearms tendons are going to be a fair amount weaker than they use to be. Sounds like a classic tendinitis symptom to me. The extra weight you gained also doesn’t help as more weight = more load on your tendons.

My advice would be to stop butting your head against the wall and climbing hard Crimpy problems and slowly build back up to your max grade over a number of weeks/months. If you feel pain after a session then you pushed too hard and your tendons have not adapted to the load.

Have been dealing with the same thing recently with my shoulder tendons - it’s a pain to have to climb below your limit but that’s the only thing that will get rid of it.