bump in the back

2 weeks after my HT, a couple days after suture was removed, I noticed a bump or swelling formed on the back of my head, right above where suture used to... Talked to my doctor, and he syringed a sample out of the swollen area or bump to find blood with serium. He recommended that I be patient about it and wait a little longer. It's been a month (6 wks post op) since the bump was discovered, and it has not subsided. An odd observation is that the bump is very small in the morning and grows bigger as the day goes on. I wonder if it has anything to do with the gravity that pulls fluid down for the bump to collect the fluid, etc while I am standing up during the day. I'm seeing a dermetoligist about it soon.