Hello,
I cannot confirm anything without examination but it can be an absecess, erythema nodosum or panniculitis. Panniculitis is inflammation of the fat under the skin. The diagnosis is established by a skin biopsy. Erythema nodosum results in reddish, painful, tender lumps most commonly located in the front of the legs below the knees.
Diagnosis is by physical examination and biopsy of the lesion.Other lab investigations like complete blood count, ESR,ASO titer, urinalysis, throat culture, intradermal tuberculin test, and chest x-ray may also be done.
I would recommend a physician/dermatologist’s evaluation. Treatment depends on the confirmation of diagnosis.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
I forgot to mention i'm 26 years old and in good health other than the leg.