all I can think of is a nerve problem. When I tried to massage my triceps one time a while ago when I did not know much about trigger points, I thought it was tight there and it was a nerve I found out I was rolling over, made my right forearm weak. I had to do forearm curls to get my strength back up even with my left arm and yes I am right handed.
I am guessing it is probably a nerve issue somewhere. Be careful what you are massaging and know where the nerves are, just letting you know.
Try these exercises comparing to your left (1 arm at a time) and let us know which exercises you have a strength imbalance in and how much of a strength imbalance. Use the same amount of weight and same about of reps for both arms starting with your weaker arm, which is your left arm...
Start with activation exercises first using both arms at once...
Wall Slides (activation)
Blackburns (activation)
Scap Push Ups (using only your scap..activation)
lying external rotations (dumbbells)
forearm curls (dumbbells)
1 arm db bench press
1 arm shoulder press
1 arm cable lat pulldown
Find your weak point and work on it, I am trying to help you find what is weak. You may have done something to a nerve like I did when I thought it was just a knott, but it was a nerve and made my forearm weak.
Out of those exercises mentioned, which ones can you do more reps on your strong side and is there a major difference in any of them?