Hey Mark,
We know what you're going through and the good news is it doesn't need to be that way. You're likely vitamin D3 deficient so ask your neurologist for the lab test for 25(OH)D. This is the serum level metabolite of vitamin D3 that's used to measure its status.
Print out the following link and take it to your Neurologist at the next appointment. It will explain the requirement for the 25(OH)D lab test...
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

In the mean time, pick up some 5,000 IU vitamin D3 liquid soft gel capsules, some Omega-3 fish oil, some magnesium and some Mature Mult vitamin mineral tabs as shown in the photo below.
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

With the exception of the Super K that I buy over the internet from Amazon, I buy these supplements at Costco. You can find similar brands at Walmart, most super markets, GNC or the Vitamin Shoppe.
Start out with 10,000 IU/day vitamin D3 for a couple days along with all the other supplements: 1000 mg/day Omega-3 Fish Oil, 400 mg/day magnesium, one of the Mature Multi tabs... You can add the Super K Advanced K2 Complex when they come in...
After a couple days bump the vitamin D3 dose to 20,000 IU/day for two weeks. In addition, take a 50,000 IU loading dose of vitamin D3 once a week for the first two weeks on top of the daily 20,000 IU dose.
At the end of the first two weeks, drop the vitamin D3 dose to 15,000 IU/day for another two weeks.
This works out to 600,000 IU of vitamin D3 over a four week period. This should result in an average 25(OH)D response of 60 ng/mL above the starting serum concentration.
After the first four weeks, drop the vitamin D3 intake to a maintenance dose of 10,000 IU/day. That should keep your 25(OH)D between 70 and 80 ng/mL...
If you're still getting hit after the first two weeks, add a vitamin B 50 tab a day and continue taking them for three months only.
Vitamin B 50 is a formulation of 50 mg each of the seven B vitamins and it's an easy way to correct any vitamin B deficiencies...
As far as being too old for CH... BS! I'll be 70 in August and I'm still a chronic CH'er... All I need do is stop the vitamin D3 supplement and WHAMO! I'll get slammed...
Take care and please keep us posted.
V/R, Batch