In all probability you have developed arthritis of the small joints of your hand. This can be osteoarthritis, rheumatoid arthritis or even gout. Another possibility is bursitis and inflammation of small joints. It can also be pinched nerve and tendon inflammation. You will need X-rays and some blood tests to find the cause. Nerve conduction studies may be performed if nerve involvement is suspected. Please consult your PCP for primary examination followed by proper referral if need be to the concerned specialist. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.