Learning that a death grip on your chords is not a good thing, is one of the biggest hurdles beginners must learn to clear. Many get away with it just happening, others focus on it and progress faster. In fact that Death Grip can actually push strings out of tune. The progression is that...you go from no grip, to death grip, to the right grip. Listen to what Iman is telling you and you will come out the better for it.

I have been told by Physical Theripists that if you have constant pain in your forearm...STOP PLAYING UNTIL IT STOPS. You don't want a chronic problem to develop and this is one of the places it can happen. Chronic Pain is where you don't even have to pick up a guitar to have pain. Don't cultivate that kind problem. If it goes away when you don't play, it is probably just normal muscle pain from the exercise you are developing. This is normal... If the pain does not stop...YOU SHOULD.