I am not aware of why you would have that side effect from Tylenol. I suppose it is possible that a deep massage could aggravate a fibromyalgia trigger point, but I have no personal experience with this. Also, I am not aware how ice therapy to your neck could cause dizziness. The neck does contribute to our sense of stability, but how the ice would affect your balance I can not explain. I wish I could be of more help. If you have not seen a headache specialist at a large academic center, it may benefit you. They may have other options regarding therapy for you. Good luck.
Strange thing is.. the pain DID turn into a migraine I think. Sometimes its so hard to tell. But light avoidance, nausea, dizziness...all indicates to me that I have a migraine.
I am so tired of them.
Massage seems not to be good treatment for fibro-- I have heard this from other people who have it also.