I was writing for almost 2 hours and i feel pain in my third finger, is writing too much caused my finger to feel pain? why is it happening to me?

Third finger pain: How are you holding your pen? In general one can develop spasm and pain due to waste products , lactic acid , etc, from any persistent static motion, i.e. standing, , staring at a computer, or holding an item persistently for an extended period of time. In any activity it is best to take a quick one minute break and shake out every 30 to 45 minutes to avoid static strain