Unfortunately, there is a lot of misinformation on this board. Stop trying to fight your spasms. The spasms are there to either stabilize inflamed areas to protect the process of healing, or to prevent further permanent damage if such damage has occurred. Stop trying to fight them, and you will actually somewhat better.
The other assorted symptoms you mention are often related to the inflammatory processes underway. Look up how inflammation works in the cases of injuries and you may get insight.
Now, the fact that you have inflammation like this tells me you don't have a good-fitting night guard. You nned to either find a good dentist who can make one that will end the pain and spasms or make one yourself with the suggestions in another post of mine. You want to try to get a good MRI of your jaw joints ahead of time, if you can, with someone competent to interpret it. The latter are hard to find.
If you want some relief, muscle relaxers only work temporarily, so try some non-benzodiazepine anxiolytic drugs. Go to a psychiatrist to get these, because dentists and GPs are knowledgeable enough to prescribe them. They may not only lesson the severity of the spasms, but may actually slow your bruxing down some too.
If all else fails, don't go in for neuromuscular dentistry or any approach that seeks to alter your bite. Go to an oral surgeon and get some Botox in the chewing muscles. Not many oral surgeons offer this service, so call around.