Hi. I have 3 hard lumps on my head the biggest one is on the left and when I touch it it hurts. I've had them for years could it be serious?

Pilar cyst. Pilar cysts are common, occurring in 5-10% of the population.Greater than 90% occur on the scalp, where pilar cysts are the most common cutaneous cyst. Pilar cysts are the second most frequent type of cyst on the head and neck. Pilar cysts are almost always benign, malignant transformation being extremely rare. Pilar cysts may be sporadic or may be autosomal dominantly inherited.
Possible cysts. They may be sebaceous or follicular cysts which are not life threatening. However, you should have them examined to get a diagnosis.