Thanks for writing to us.
As per your own admission in history, you have not injured your head at all.This rules out Scalp Haematoma
The small finger tip sized swelling you are describing on the left Parieto Occipital area in all likely hood is an enlarged sebaceous(oil producing gland) gland due to blockage in its pore.We call it a Sebaceous Cyst
.If it becomes infected then it becomes painful.Appearance of multiple sebaceous cysts are common on scalp .
Under local anaesthesia ,after routine investigations it can be removed by a minor Surgical Procedure called "Enucleation"ie., removal of enlarged sebaceous cyst along with its capsule and its contents.
Kindly approach a qualified Gen Surgeon for the same.
You need not fear it to be malignant at all.
Wish you a speedy recovery.,
Dr Lt Cdr ASN Bhushan.