Hmmm, neck tension that is diffuse and focuses on pain behind the eyes....
Hello, I just saw your post, and thought I might offer some ideas about your "headaches". I put headaches in quotes because it sounds like your pain is really not a pounding or sharp pain in your head, but focusing more on general neck and shoulder tension and a feeling of pressure behind the eyes - am I correct?
By the way, in addition to a martial artist, I am a graduate of an acupuncture program, and if you are willing to take my opinions as information only (as the site disclaimer says), and not as gospel, or worse, a diagnosis, then I have some thoughts.
Such signs/symptoms as described can occur due to many reasons, but ruling out a more serious medical condition, you may have what we in classical chinese medicine refer to as Liver Qi Stagnation, Liver Blood Deficiency or related patterns. These names are metaphors which describe how energy (Qi, Chi) becomes blocked, much like a dam in the river, which prevents your energy from circulating smoothly. This leads to a feeling of stuckness and pressure point sensitivity, particularly on the high points of the shoulder, along the trapezius muscle, as well as tightness beneath the rib cage, slight irritability, dull pain behind the eyes and/or on the top of the head, etc.
Liver Blood Deficiency is another, slightly less metaphorical description of a condition of long term stress and overwork which taxes the body and depletes the overall nutrition and body fluids. If you also have difficulty getting to sleep, or more often than not wake up in the middle of the night, see spots or "floater" in front of your eyes, and have general tension in most of your joints, then you might also have Liver Blood Deficiency (or Liver Yin Deficiency). This might also cause your behind-the-eyes pressure pain.
What to do? the others offer excellent options for you, such as taking time during the day to close your eyes and breath. Reflecting upon your thoughts, much like what occurs before we go to sleep at night, but doing it more often during the day is a great way to unwind accumulated stress which can cause the Qi to Stagnate, and the Blood and Yin to become deficient.
Massages on a more regular basis, and of course, acupuncture and herbs from a qualified licensed practitioner would be helpful, as well. You can do acupressure on your own, by pressing gently into tender points on the inside area just above your knees, massaging gently just under your rib cage beneath the diaphragm, and also around your belly button until the area is comfortable and warm. This will promote healthy digestion and calm your nervous system (by bringing energy down to the dan tien/hara).
You can also get more sleep, and change your diet to eat more nourishing and warming foods (especially with fall and winter approaching). I won't say more without seeing you in my own practice, but these are general health recommendations you'd find in any alternative or chinese medicine book.
Hope this helps.