Pain in left hand middle and ring finger joints in morning?

Arthritis could: Be playing a part especially if you have had an injury in the past. Outside of that it could very well be a trigger finger if it is an isolated finger. Typically it will feel stiff in the morning and may lock-up. You can try extension exercises. Icing. It may require an injection to help it. If it is not getting better seek the advice of a hand doc or orthopaedic surgeon.

Nerve pain: There could be several possibilites. The pain can arise from your arm/elbow or your neck. Usually it happens when the nerve is oinched in one or both of these areas. See your doctor.