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1.The history and symptoms suggest the possible cause will be
ganglion at first place followed by hair
follicle infection,
lipoma.
2.Ganglions arise from the joint space, tendon, ligament, bursar,nerve sheet - which when complicated cause the symptoms.
3.In this case an
ultrasound lump to evaluate the nature of the lump its source and extensions.
4.Depending on the findings the treatment will be small
incision and drainage followed by wound dressing and antibiotic treatment.
5.So i would suggest to get an appointment with the GP, get examined and needful treatment. Good luck.
Hope i have answered your query,
any thing to ask do not hesitate to ask.
http://doctor.healthcaremagic.com/doctors/dr-ganesh/62888