Is it normal my hand is bruised without cause?

Last night a bruise appeared on the inside of my thumb/hand.
My hand feels sore but so does my other hand that isnt bruised.
All I have been doing is sewing and I have arthritis in my family but im only in my 20s.
My wrists feel stiff and like ive strained them.
The bruise is already a little lighter than last night when it was very big and dark but its there.
I dont know what I should do, I guess just rest my hands.
Ive had carpal tunnel syndrome but that was over a year ago..