Hi,
You may have engaged in certain exercises that may require straining or exertion.Straining may cause an increase in blood pressure and also affect the flow of blood to and within the brain.This sensation of head fullness may need to be assessed.Your blood pressure may also need to be evaluated.
As one stands abruptly from a lying down position, a feeling of dizziness or faintness may be felt. In your case ,you have noted a certain pressure within the head.I suggest that you refrain from doing the exercises until you have been thoroughly assessed. From a lying down position, try to stay seated for a while before standing up. A CT scan and evaluation of your neck vessels may be able to help.
A thorough assesssment of the ears,eyes and sinuses will help rule out any involvement of these structures.
First, let me say that I am not a doctor, but I have experienced the same thing you are describing this month. I am only 25, and it worried me a great deal. It turned out that I had an ear infection without knowing out, and my sinuses were clogged. I had never had that kind of pressure in my head, and it only felt that way when I would lay down and stand up. I was prescribed Nasonex and OTC Claritin, and so far it seems to be working. I still feel the pressure, but it has been slowly going away. Good luck KatiJ!