Re: Bells Palsy?
Bell's Palsy is one of those things that can be caused by just about anything, or just show up with no good reason. A lot of the viruses that can cause it may not cause any other symptoms. You might ask the docs about an anti-viral med in case it is caused by a virus. They would have to weigh the risks of giving him an antiviral that may not be needed, with the possible benefits of it if it is a virus. I'm not even sure what the risks of those meds are.
In most cases, though, it's not particularly important to establish the cause. You most likely don't need to explore expensive imaging tests unless he doesn't get better as expected. Especially if you believe that it was caused by either the massage (which would presumably have compressed the nerve at the time but should not result in ongoing compression) or a virus (because this is the most common cause, and the massage could just be a coincidence), a ton of tests might be overkill at this point.
Of course, the doc may ask for a ct scan to look for some of the more rare causes (infection or tumors along the course of the nerve), especially if things don't improve.