Recently had a possible seizure and i am now having trouble unclenching my left hand. is this something serious or will it go away.

Neurology evaluation: A face to ace evaluation is needed to figure out what is going on. You might be experiencing partial seizures or muscle tightness. Only a good evaluation can help figure this out.

Testing?: If your MRI and EEG are normal, then it's likely going to pass with time. If they aren't normal, discuss this with your neurologist.