Maybe get some straps and try isolating the bicep? I remember having pain in my forearm on arm days and it was because I wasnt connecting with my bicep and the forearm took most of the load. Also stop egolifting and use weight you can feel the bicep contracting. .02
I've tried the straps and I just felt it made it worse. I backed off straight bar for a while and it stopped. Then slowly started back up and I've been fine. I also pop ibuprofen before I lift.