<s>[INST] I had this lump in the back of my head for years. The last few months it has been hurting badly. It is like a knife going in and out. Also I have been dizzy for the last few weeks and lost my balance a few times. I cannot even walk without hanging on to something. I finally lie down and do not move.  I cannot see my doctor for another few weeks. [/INST] Respected user, Welcome to Chat Doctor.come have evaluated your query thoroughly.* There are different reasons for lumps of the head.  Which may vary from benign soft tissue lesion as sebaceous cyst, others or certain tumors as Osceola or others.* Need clinical examination for the same, evaluation in form of CT or MRI according to the clinical evaluations to decide further line of management. Hope this will help you for sure. Welcome for any further guidance. Regards dear take care. </s>