Unfortunately I am able to relate to you symptoms. My wife had botox once, and although she had several other symptoms, for several months the pain in her neck and upper back was unbearable. You are not alone in this!
From our discussion with other people around the world, pain in this area is "common".
I would like to put it out there that I am not a conspiracy nut, I don't rally against "big pharma", I am not trying to promote anything. Please don't write me off even if my reply seems to contradict these statements.
I have a genuine concern for people who are suffering after getting botox injections. I fully acknowledge that the risks of adverse effects after injections are very low, but its for this very reason that there is not much know about the side effects. This means that people who do have side effects are left feeling alone and unsupported.
My wife and I created botox support community to collect peoples stories and to help support people. There is no profit, we gain nothing from it.
If you like please have a look and you will see other similar stories.
I hope that this passes for you soon, and that you can get back to leading a great life.