Why does my radius bone in both of my arms hurt after arm wrestling? it only hurts when i lift weights and this never happened before?

I'm not sure you can differentiate bone pain from muscular pain. In my opinion, muscle strain or overuse is a much more likely cause of pain after lifting weights or arm wrestling. Is your lifting technique good ? Have you increased weight amounts or reps too much? Abstaining from those activities for a week or so would give the arms a chance to recover.