Brief Answer:Muscle fatigue
may be the reason
It's good to see you
After going through the whole discussion, it seems you have developed muscle fatigue .My suggestion for you would be-
1.You must have diet rich in calcium (1000mg/day),Vitamin D (800 i.u./day) protein(1gm/kg body weight)along with vitamin B6 and Vitamin B12
2.Regular muscle strengthening exercises of hand like pressing the soft ball or lifting up of dumbbells.
3.Take pain killer like Ibuprofen
on as and when required.
Hope this helps.