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1.The history suggest most possible cause could be
ganglion.
2.A ganglion
cyst is a fluid-filled bump that forms under the skin near a joint, most commonly in the wrist area,sometimes in the shoulder, elbow, hip, knee, ankle,foot regions.
3.They generally arise from the joint space from synovial space, tendon, bursar,tendons and
nerve sheet.
4.Normall its monitored but since you are symptomatic needs aspiration or
incision and drainage followed by antibiotic course.
5.Most appropriate specialist for this could be orthopaedics - so get examined and treated accordingly. good luck.
Hope i have answered your query.
Any thing to ask do not hesitate
http://doctor.healthcaremagic.com/doctors/dr-ganesh/62888 Thank you.