Lumps under the head are relatively common and usually caused by hair follicles that have clogged and become inflamed. Inflammation of the hair follicle can often be painful but will eventually pass. There a number of reasons for follicles to become inflamed, and the condition generally does not require treatment.
Hair follicles are the cells that hairs grow from. They are found underneath the skin. The shaft of the hair grows from the follicle, growing through and then out of the skin. The follicle is attached to a gland that produces oil, which travels through the follicle, up the shaft of hair and spreads across the skin as sweat.
Hair follicles can become inflamed for a few reasons; when they are on the scalp they can cause lumps to form. The follicles can inflame because of ingrown hairs, clogged follicles and boils. Lumps caused by these should go away over a few days. If your symptoms persist past a week you may want to consult a physician.
Ingrown hairs occur when the tip of a hair shaft growing through the skin curls before it has broken the surface and grows slightly into the skin beside it. This causes an irritation of the skin and in some cases infection. The tips of most ingrown hairs are pulled out by the continued growth of the shaft, but in rare cases the hair ill continue to grow into the skin and spread the irritation. In such cases surgery is sometimes needed.
Occasionally, the oil that the sebaceous gland sends through the hair follicle gets clogged, clogging the pore that the shaft of the hair passes through. This causes the pore and sometimes the follicle to swell and make a lump on the scalp. When this happens on other areas of the skin the effects are generally called acne. The lump may fill with puss and be slightly painful, but it will eventually go away.
Boils are caused when a follicle is damaged and becomes infected with many of the bacteria that live on the skin. When this happens, the follicle and the surrounding skin begin to swell and a lump soon appears on the surface of the skin, which fills with puss and dead cells and can be quite painful. The boil will eventually drain on its own, but can be drained before.