What Causes Loss Of Mobility In Fingers And Arms?

hi doctor andrew .i am denisa 26 years old, i read this page and i would like to ask for a prblem that i have with my both hands, sometimes i feel that i lose the power in my fingers and arms ,i cant even keep something or move the fingers .im very terrified about this problem. please can you explain what is happening with me , what can i do ? thank you