Ok, so I have been doing more research on masticatory myocisits and this is what I found:
"Masticatory myositis can be divided into an acute and chronic form. It must be remembered that one acute attack can lead immediately into the chronic form of the disease, although, more often than not, multiple, recurrent acute attacks are necessary. Symptoms of the acute form involve the the swollen, firm and painful temporalis and masseter muscles. The dog's head often appears swollen and larger than normal. The dog will be reluctant or unable to open his mouth. Opening the mouth more than 1 inch or so elicits an extremely painful response. This results in difficulty in eating and often the owner notices increased drooling as well. This swelling may even cause exophthalmia or the eyes to "bug out". Usually a fever is present and the lymph nodes in the head and neck region are enlarged. The tonsils are often enlarged as well, but it is difficult to visualize them due to the inability to open the mouth. The patient is often depressed and may resent palpation of the head musculature.
In the acute form, there is usually rapid clinical improvement."
This sounds JUST like what happened with Gus. He had a fever, the drooling, the pain around all those muscles and didn't want anyone close to his face, and the swollen lymph nodes, everything! The internist acted like I was an idiot because I wanted the test sent out anyway. No, she would rather test him for cancer and freak me out!!!!! (I am a little bitter now) I asked her if there is an acute form, and she just acted like I was dumb! It's explains why he got better so fast. I wonder what the test results will show. I hope they sent out blood that they drew during the time he was painful, and not the day he was better. I have read that 15% of dogs that do have it, still test negative! Hopefully, if that's what it is, and I have a strong feeling that's what he had, I hope he doesn't have another flare up or ever go into the chronic form. Of course, I hope he doesn't have anything wrong, but it would explain a lot if it did come back positive. The ER vet, the one that suggested to test for the MMM, said that his liver enzyme that was high could be affected by muscle damage, but the internist didn't think so. I have read about elevated ALT levels and they can be elevated due to myopathy (muscle disease). I should print this out and send it to the internist. But then if the test comes back negative, I will just look dumb, LOL. I just hope I get the results soon!
And good to hear Gus is feeling well enough to bark.. 
More healing vibes to him.
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