From what you have just written, and my own experience, it sounds like neck (cervical spine) issues might need to be investigated. An MRI via neurology. I also have found a good PT to be good diagnostically.

I benefit from topicals- either creams or patches. This might be a good way to see if something is going on in neck. You said one side feels firmer than the other, which could be muscle tension. This can be caused by "myelopathy" or a cervical vertebra being even slightly off position. Neck spine issues go all the way down the body as well as up the face and scalp.

Maybe try Ben Gay (my favorite) or BioFreeze. Ben Gay has a greaseless formula (green ) and extra strength (red). Massage it (I put a plastic bag over my hand) on the place that feels firm, anywhere that feels sore to the touch, and on the other side too. See if that has any effect!

This is all just my experience and of course you need MD's to advise. Again I have found a good PT to be extremely helpful diagnostically and that has helped me avoid some testing. Hope you can get a counselor for support!