When ever i qualify with my sidearm, i get a shooting pain on my right hand. this pain originates behind the thumb joint and the wrist after the shot

Tenosynovitis: I think you are experiencing DeQuervains tenosynovitis which is being caused by excessive muzzle whip because of grip or firearm grip angle.

De Quervain's: syndrome (tendonitis of the extensor tendons about the thumb) can occur in folks who shoot pistols frequently. Shooting can also worsen symptoms of thumb and wrist arthritis. If symptoms are a significant problem a rheumatologist might be able to clarify things.