What could it mean when your right arm an hand suddenly gets tigly an numbness in it every so often?

Three main areas. Carpal tunnel at the wrist form overuse or computers, at the elbow from resting the elbow on a surface or bed, or from the neck from a pinched nerve if you have problems there. Thoracic outlet syndrome could also be involved. Otherwise the causes would be more unusual such as B 12 or folate (folic acid) deficiency.