Having Finger Twitches

Hi, i was going to text on my cell when i was going to press a letter with my thumb and the thumb started twitching like crazy!! i pulled my finger away and it stoped and moved it like to losen it.. and did it again and it just twitched away. tried it with my other thumb and that one also twitched.. it's been happenn for awhile now i have numbness in my arms,my neck and back hurts not sure if it has anything to do with that.. can any one give me any ideas of what it could be... rite now that i'm writing online it's not doing it but it happens at least 3 times in one day..
                              Thank you