If you have a friend or associate really work that area does the pain lessen during the stimulation, only to crash back down once they let go?
I usually associate headaches that start at the base of my skull with tension/stress headaches (and stress can be generated a lot of ways) and with the whiplash I got back in the 80s. Oh, and smoking probably didn't do my neck any good (the nicotine seems to reduce blood flow into the spinal cartilage, especially in the neck).
These would be most effected by the "THC" cure noted above (probably illegal), and/or by doing stuff to reduce stress over time (sex/masturbation to orgasm, hard exercise (did you ever get access to a swimming pool?) on a regular basis etc. etc.. Yoga and/or Feldenkris might also help. These things are preventative, not curative, so you'd have to look at what didn't happen rather than attempt to apply them afterwards. Although I guess there's no downside to getting yourself off after the headache starts, if it helps in the end.
You mentioned "above" that going to the doctor would be expensive and time consuming. Are you under 26?
I will try getting someone else to rub my neck next time this happens and I have someone handy. When I do it myself, it doesn't so much affect the headache as serve as a distraction therefrom.
I still don't have access to a swimming pool.
I am under 26, and I am on my parents' insurance, but the problem is that sometimes I turn out to owe money for miscellaneous doctory things and doctors don't or can't warn me which things these are, they just say "okay we're going to do this thing" and then it turns out I need to give them thirty dollars for this thing. Even when I remember to ask "hey is this going to cost me money" they seem not to know, since I suppose it's insurance-dependent.
I've been collecting data about my headaches and diet for almost four months now. I don't see any patterns - annoyingly, I get headaches nearly every day, so there's not much information - but I thought I'd post the data set and see if anyone sees anything. Here it is. Hopefully someone finds this an interesting problem.
It's written in note-to-self format (abbreviations like "strawbs" for "strawberries"; if I mention a complicated dish once then I'll shorten it when I eat the leftovers, as "pasta" for "pasta with artichokes and spinach and pesto"; times given approximately and not in a consistent form and often without specifying if they're a.m. or p.m., though they are in chronological order). Quantities aren't given, although if they're suspected to be relevant I may be able to remember specific instances (for unusual foods) or typical portions (for ordinary foods) - other details might also be recollectable similarly. I also don't notice when headaches go away, so I don't know how long they last except when they last all day or become noticeably worse during their course. My sleep schedule varied considerably over this period, but trends more night owl than early bird (for a while I was outright nocturnal). I moved three time zones west at the end of July, should that matter at all.
I'm not soliciting commentary on my diet except insofar as it can be compellingly related to my headaches.
ETA: Assume that every single day I'm drinking lots of skim milk. (2-6 cups depending on how much I eat and how it's spaced out.) There's a couple of exceptions, mostly when I'm in transit for most of a day or run out of milk, but not many and they don't seem to correlate with headaches.