@ksdm there are a ton of muscle relaxers in different classes. Tzanidine worked extraordinarily well. I was recently put on Baclofen which works in a different way. I didn't see that you tried MFR therapy (there is a group on that here) or Botox. The botox IS FABULOUS. I have done it since 2013. It was just what I needed THEN. but eventually I had surgery. With the entire nightmare of surgery it didn't repair or stop the muscle spasms in my neck/shoulder area.
You will need to understand WHY you have it before you can treat it properly. After a lifetime of problems, I realized the neck trauma from 4 whiplash accidents AND my career as an artist has put my neck in permanent "spasticity." It is dealt with differently than a muscle spasm which can be healed after a massage. I still wear one of those foamy neck cushions periodically to relieve the pressure and I still try managing with great outside therapist MFR 2 times a month and I get a bit of MFR from the P.T. guy every week. Spasticity means that there is a nerve root from your spine impinging on nerves causing the spasm. That is the bridge I am on right now. The CPT code and treatment is different. good luck!