My left arm feels weird mostly at the top of my arm, it feels kind of weak but feels good when i massage the top of my arm and it feels like i cant do things with it like its slightly numb eventhough i can still do things with it?

Acute focal weakness: don't have enough information but enough to know you must be evaluated ASAP. Possible causes of focal numbness and weakness: stroke. Are you prone to clotting? Pinched nerve in my neck – have a history of neck injury? Multiple sclerosis? There are many not so scary causes, but you need to go see a physician or Emergency room now.