I too have been living with the same problem for years. I have found yoga to be the only thing that really helps. Particularly the inverted poses. Infact the inverted poses have been the most effective way of releiving my neck & shoulde rmuscle tension (Please google for further info). These poses are a bit tricky so I would suggest you consult a yoga teacher. You also want to try the fiollowing breating pattern. Breath in for 4 secs, hold your breath for 4 secs breath out for 8 secs. Holding your breath retains the carbon dioxide in your blood stream which will naturally make your muscles relax. (Google anxiety breathing, there's loads of info available).
Hope this helps
Good luck
You described me to a tee back 12 years ago...I had a non-stop tension headache with anxiety for approx. 6 months straight. Pain meds (even prescription ones) didn't help me at all, just made me groggy with the pain and pressure (like in a vise like nikogal said). I went to a neurologist and psychologist at the time. The psych put me on Paxil (which I am still on to this day) and the neurologist put me on depakote. (it us usually for seizures and schizophrenia, but it worked on my headaches!)...Within weeks to a month, I was a different person. I was able to function and my anxiety and headaches subsided and continually got better. After a year I was off the depakote, but remain on the Paxil (and klonopin when needed). I am not 100% better after all this time, but I would definitely say 98%. I still get anxiety (but definitely manageable and not all the time) and an occasional tension headache (but not debilitating as they were), but it does not interfere with the quality of my life. Hope this helps.
Also, it gets much worse if I am anxious..it makes me even more anxious. It feels like your head will explode but I dont think it has anything to do with blood in your brain.
I had a time of great anxiety where it felt like my head was in a vice or some Sumo wrestler was sitting on my head. Funny it didnt hurt, just alot of pressure. I went and had my neck checked out and I had a loss of neck curve (probably from anxiety or bad posture). I got some physical therapy and was better. Sometimes it comes and goes but if I sit and think about it, it gets way worse and doesnt go away.
I have aneixty and I get horrible headaches... my neck and back kill me.. I have been going to all kinds of doc to try and get help but.. I haven't found any... I think som eis from me sinuses but my neck and shoulders are alwyas really tight... I wish I new what to tell ya but I feel some of your pain...
Good Luck