Hello and welcome to healthcare magic. I am Dr ASAD SAMI and I have read your question.I can understand your concerns and I will be answering you .. What is your age.?? Are you diabetic or do you have its family history..?? Any history of chronic disease..?? There are lumps anywhere else or not..?? Lump is painful or not ..?? Do you have fever .. ?? If i were treating you in my clinic i would have palpated that lump to look for its consistency.I would have looked for its mobility under the skin.i would have done skin pinch test to rule out sebaceous cyst or lipoma..according to the information you presented it seems that you have developed a sebaceous cyst.these cysts are most common in hairy areas.these cysts develop due to blockage of the duct of sebaceous glands.thus the gland is unable to empty its secretion(sebum) and it enlarges with the passage of time.sebum helps in the lubrication of hair.the diagnostic point of sebaceous cyst is a punctum(hair follicle on the surface of the cyst).the definitive treatment of sebaceous cyst is its surgical excision which is a minor procedure done using local anaesthetic such as lignocaine or bupivacaine.you will be able to home right away. 2nd on my list would have been a lipoma.lipoma is freely mobile under the skin and one can pinch skin overlying it.If lipoma is causing problem ie cosmetic problem or in your case interfering with you sleep,then it needs surgical excision.It is also a minor procedure. 3rd on my list would have been an abscess.abscess fluctuates when one puts two fingers on it and presses one finger.mature abscess will need surgical adequate dependant drainage.a trial of antibiotics such as amoxicillin plus clavulonic acid or flucloxacillin can be given. Others on my list would have been boils,any fungal infection or some malignancies such as squamous cell carcinoma and basal cell carcinoma for which i would have taken excisional biopsy and would have sent for histopathological examination. I will suggest you to meet a general surgeon for a second opinion.In the mean time remain calm and dont worry.keep the area clean and dont injure that area while combing hair. Thanks. Hope the answer is helpful. Feel free to ask further questions. Regards.Dr Asad sami