Welcome to HCM.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided.
Palm pain can result from damage or injury
to any of the structures in your palm, including bones, joints, tendons, nerves, muscles, blood vessels, connective tissue
, or skin.
History of injury should be exclude, presently as you are having pain and swelling i advice you to take NSAID's, these are available as over the counter drugs it will help in reducing the pain and inflammation.
I advice you to see physician for examination for exact diagnosis.
Hope I have provided the information you needed.
Wish you good health. Take care.