I'm afraid you'd have to be a medical expert to be able to offer an answer. Vitamin D deficiency is quite common nowadays because people just don't go out in the sun at peak hours anymore--a half hour in it is all we need absent some problem the body has in synthesizing the stuff. The D dosage is a lot higher than he needs, but it's for a set time period. D deficiency can cause a lot of symptoms. The fact he was getting tired in the daytime might suggest sleep apnea, which the neurologist apparently failed to consider, bit if that has gone away, that might explain it. It could be a magnesium deficiency, which is also quite common nowadays as people eat a lot dairy but not as many green leafy veggies as they should, which leads to too much calcium and not enough magnesium, as they can leach one another out of the body if they're not in the proper electrical balance. Magnesium plays a very large role in nerve health. I could be a neck problem, with discs or bone spurs pinching on nerves that go up into the head -- I have this problem. It could be a side effect of medication, but you don't mention that he's on anything until the doc did what docs do and instead of recommending lifestyle changes just gave him a drug for BP. Those can have lots of side effects, but this happened before he was it. Also, the thyroid test he was given probably wasn't a thyroid test, it was probably just a TsH test, which measures nothing in particular. Only a test of his T3 and T4 and how they interrelate would answer that. Could be a B vitamin problem, as some people have a problem converting B12, folate, and B6 to all the forms the body uses them for. For us amateurs on here, we can only hope your docs are doing all the right things and not just moving patients in and out of the office. As for the MRI, if your husband has no problem taking them, they aren't harmful, so if he's got no phobia about them it's not going to hurt him any. But if he's going to do that, he'd probably want to make sure the MRI doesn't just look at the brain but also the neck just in case. Most of us just do what the docs tell us to do because we usually only really learn things once we get a good diagnosis -- you can't just research symptoms but you can research best treatment once you have a diagnosis. So I guess you do what the docs are trying until you get to the point where you think they're not doing enough, and then you find better docs. Best of luck.