Possible tumor, advice?

Hey friends! Brand new member here and just wanted to get some input from others and their stories. I'm aware that no one will be able to diagnose me here but I just feel a lot of anxiety and would like to see if anyone else has had similar experiences. I found a lump on the back of my head, right side, middle of the ear level, according to the ultra sound 1.5 cm big. My doctor has scheduled me for a CT scan this coming Friday and I am so very nervous that it could be cancer. MY PCP said it was definitely a nodule, but was completely unsure of what it specifically is. The nodule is like a I said 1.5cm, so quite small right now. I have no idea how long it has been there because I really just never noticed it, however I've just cut my hair short in the last couple months that you can see my scalp. You can definitely feel it under my skin and it is very hard, not mobile at all. The non-mobile factor is the most concerning to me. My family members have said that it doesn't feel any bigger from when i found it acound a month and a half ago. I have been expereincing some balance issues and some fatigue but I also have anemia, so it could be that. My PCP seems a little concerned, so I'm extra nervous about it. There is no white head or anything pointing it to be a skin problem. My PCP also said that the CT scan is basically to see the specifics and to see if it has a blood flow. What will it mean if it does or does not have a blood flow? Is a nodule another term for tumor? And has anyone had an experience similar to mine? Was it diagnosed as cancer for you? How did it go? 

Thanks so much for anyone's input or just thoughts.