Three nerves innervate the hand/fingers. Ulnar, median, radial - the fingertips(the soft,fleshy part) reflects median nerve for p,i,m,a, and ulnar for c. Is the numbness permanent or does it resolve after playing guitar? If it is permanent, then there nerve injury. If it resolves after not playing guitar, then it is probably median nerve impingment and may reflect too much wrist flexion, in which case altering wrist position may solve the problem. Most of the time such a problem goes away by altering wrist mechanics. Wearing a resting wrist splint at night for a week or so can sometimes reduce nerve swelling/inflammation and solve the problem. If the numbness is permanent, see a neurologist or a neurosurgeon. Circulation failure in the arms is EXTREMELY uncommon - I've only seen it in folks who have had diabetes for many decades - usually type 1.
I like to do work around the house - carpentry, ceramic tiles, etc. When I do someting that requires a lot of work with my hands, I usually have some tingling in my left hand for a few days when playing but it resolves.