I have a knot on my head. what could cause this? noticed it doubled its sized yesterday. & now i have another one above my ear. should i go to hospita

Possibly a Boil: Many causes of a knot on the skin. In your case, being that fast growing, I would think that it might be a boil Usually they settle in few days, and at times it might cause some pain at the site due to pressure build up from the fluid under the skin. I do not think that you need to go to hospital for that, unless you start feeling unwell Hope you get well soon

Blocked gland: A sebaceous cyst is a collection of oily fluid that occurs when an oil gland is blocked. Some folks are more prone to them than other and they often appear on the neck, shoulders, and back. Try to avoid skin products that are oily. I would also stay away from transfats and bad oils, which is good for overall health.Saunas and sweating may help a bit although i don't of data. See doc for Dx.