Hi,
From your post it seems very likely that what you are suffering from are tension headaches. I would suggest you to make some changes in your lifestyle. Make sure you do not skip meals. Meals should be healthy, light and comprise of fresh foods. Drink plenty of water during the day to avoid dehydration. Avoid caffeinated beverages. You can also cut down on your smoking and alcohol consumption.
Hopefully these changes will relieve you of the headaches. Do keep us posted.
A "stiff band tied tight around [your] head" sounds like a tension headache to me. And... even though you don't have any muscle pain anywhere else in your body... the pain in your head... well, those are probably head muscles that are hurting if it feels like a stiff band tied tight around your head.
A bear attack and having to use bear spray or having a friend have to use bear spray is a pretty traumatic sort of event and could have totally stressed you out!! Even if you didn't feel stressed emotionally or intellectually... the body reacts to that kind of thing... you have a built in survival mechanism to help protect you in situations like that which floods your body with "flight or fight" hormones and chemicals... afterward, when you are safe, sometimes you will still have a left over of those chemicals, and an over-dose of those chemicals can sure do a number on our bodies!! because.... they are stress hormones!! so, it makes perfect sense that even if YOU are fine, your body might still be stressed out!
try to help your muscles relax by taking an over-the-counter drug such as advil as long as you are not allergic to the ingredients. but... don't do this for more than a day or two as too much advil for a pro-longed period of time can actually start to cause rebound headaches. but, advil for a day or two should start to help the muscles relax. or, you might need a stronger muscle relaxant... but, if you haven't taken one of these before, you might find that they are too strong (they make me hallucinate) although if you have taken them before and you haven't had any ill effects... try one of those and see if it helps the muscles relax.
you could also go to the doctor and see if he does trigger point injects to help the muscles relax, if he doesn't, you may need to ask him to send you to the hospital or a pain clinic for this... he should know where to send you or if this is even needed (or if he just needs to prescribe you something stronger than over-the-counter stuff).
you can also try massage (although for some people this can aggravate the muscles more... so ask them to take this into consideration... let them know you are ALREADY in pain), acupuncture, or a heat pack or a cold pack on the sore muscles... even a warm shower might help.
now... you could always go to another doctor too to get a second opinion about if the bear spray could have had any negative effect on your system... just to be sure, if you think it might have.
or, you could go back to the doctor you already saw, tell him you are still having headaches, and ask him for a specific diagnosis, and if he gives you one of tension headaches, ask him for treatment options. (or, if he gives you another diagnosis... probably migraine or sinus, ask him for treatment options for those types of headaches).
I could TOTALLY be wrong on the tension headache thing though... so let us know how it goes and if you get a new diagnosis from the doctor, let us know what it is.