I Often Keep My Hair In A Bun On The

I often keep my hair in a bun on the top of my head. I now have bumps on the hairline on my neck. Some have healed but then others pop up. They don't itch but they can be painful. There is no fluid in the bumps. They appear to be just hard painful bumps. Could they be the result of having my hair up frequently? Is there anything I can do to cure them besides not putting my hair up? (If that is the problem) Thanks!