wow. Very long question.
1. The nasal spray is fine to take on a long term basis
2. Amytriptyline will help with jaw clenching and stress, as will many antidepressants. It is key to stay on it to break the cycle.
3. A gel mouthguard is absolutely necessary. Its not just to protect your teeth. It greatly decreases the force at which you clamp the jaw together and decreases mouth injury. You should wear it.
4. You really need treatment for anxiety, a good recommendation would be Zoloft. Its great for overall anxiety disorder. I think your Gp is wise to stay away from diazepam as its habit forming and won't work long term.
5. A muscle relaxant like Flexaril can be very helpful in the short term, and is also very good for neck spasm.
I hope this points you in the right direction.
Thanks Dr. K.
I guess I'll have to see if my GP will prescribe either of those