What Causes Headache And Pressure In The Back Of My Head?

Hi! First of all I should say that I am a medical student so I look into things more than I should. So here is my question. I have an average BP of 116/67, average HR is 65 and average PP (pulse pressure) is 49. I also have to state that I have a sinus bradycardia of even 50bpm at sometimes. Holter is OK, heart echo is OK.. all with normal findings. Bloodwork seems ok also. TSH, FT4 levels are OK. Everything seems OK, but lately I noticed that I feel tired a lot during the day like I havent slept. My heart goes around 100bpm when standing (not everyday) and I feel pressure in the back of my head and a rushing fluid. I also feel inside my head strong pulses from time to time. My BP seems this week goes like this. 115/65 when I wake up, 112/64 3-4 hours later and around 17:00-18:00 goes at 118/70 and stays there. 6-7 months ago I went through mild depression (nothing serious). What can I do to feel better and stop this headache/pressure in the back of my head? A head CT-scan has been done and it looks fine.