For At Least A Few Weeks I've Been Wearing My

For at least a few weeks I've been wearing my hair in a high, tight ponytail. I usually never wear my hair in a ponytail and I've been going to sleep with my hair in a ponytail too. I was feeling around my head a moment ago and I realized there was a thumb-sized lump, with a small dent directly under it near the top of my head. Should I be concerned about this?