Welcome and thanks for posting on HCM
This sounds to me like arthritis. This could be due to gout or an infection (particularly bacteria infection). Your doctor will need to do a scan to make sure that your bones are not affected.
Cellulitis needs to be ruled out by your doctor.
Some blood tests ( for signs of infection) and uric acid tests will need to be conducted to confirm or rule out septic arthritis
If infection then a course of antibiotics such as cloxacillin
etc can be started combined with antiinflammatory drugs.
If gout, then antigout medications such as allopurinol
could be started to alleviate the symptoms. (NB gout is not very common on upper extremities).
Hope this was hepful