Rbear, sorry to hear your are going through this. Dystonia can hit anywhere. Sounds like you have Cervical, which is pretty common. The legs locking up could also be dystonia - this is usually known as localized dystonia. You should look up the Dystonia medical research foundation or DMRF website https://www.dystonia-foundation.org/. There is lots of good information on the site. Make sure you have a good doctor that you are comfortable with and you should consider seeing a movement disorder specialist.
Take care, Jnufish

I have the same problem with my legs and feet I can't relax the muscles into normal positions which makes my feet turn inward and my toes tense up and lock in a curled position like I'm grabbing the ground with my feet
I just had surgery they did tendon splitting and lengthening to pull the direction of my foot back but I still am waiting for the to make my brace and my dr wants to do surgery on my Achilles' tendon to then after that the other foot

I too also have an issue with sweating like crazy I'm not sure if it's medical condition or from medications but what I just started using and works great is a spray deodorant You can use on other areas you tend to sweat more

When my legs lock up from stiffness it is hard to walk. I take Epsom salt baths to make me more relaxed and less stiff this might help you. I don't know if you are describing stiffness. I have dopamine responsive dystonia everywhere in my body. Dystonia could be come progressive. Mine got worse overtime. It is scary to loose your body and mind to this condition. It is not easy and depending what you have it could be painful bc of the stiffness. I hope for the best for you. Don't loose hope and when you become depressed the shaking becomes worse so talk to someone about your feelings and find a good way to cope for yourself.