I too get forarm issues when doing curls. But I also do bent over rows and pull ups so my biceps and parts of the forarms get a lot of stimulation. Where it hurts on me it is on the inside of my forarm, just on the outside edge of the crease cpntinuing toward my hand.
I think it is related to the bicep tendon attachment.
Anyway I have tried all sorts of carzy stuff. But one thing that I found to REALLY help is this;
You need to get some Deca and some DMSO. I use a slin pin to shoot the Deca directly into where it hurts. But dont go too deep, no need to, the DMSO seems to carry it in to where I need it..
These are multiple micro injections. I do like 8-12 in the painful area just under the skin.
Then I hit it with the DMSO 3 or more times per day. This is the only thing that I have found that really gives me any real relief.
Have tried Cysus, Heating rubs, Heat, Ice, etc. None of that really helped much.
This probably seems kinda extreme to you, but this was stopping me from working out.
Good luck!