Thanks for the responses.
The cramping I'm talking about is just muscle cramps in general, particularly after working out. I think it might be related to lack of glucose, since I'm fairly low carb compared to what I used to be, and it is worst after a few days of high activity. I bicycle commute, and after 60 miles in a few days, if I didn't get enough carbs, my muscles are very prone to cramping. Of course there are various vitamins and minerals than can cause this as well, all of which would give similar symptoms if I was getting some in my diet, but not enough to keep up with intense activity.
So, Tyler, I don't think it is related to B vitamins. I do eat a decent amount of mixed organ meat (3/10 of a pound per day on average), as well as 2 pounds of high fat ground beef. (All from Slankers, somewhat similar to Lex's diet from a while back, I assume he still does something like that).
Re: brewer's yeast - I'm sorry, that was a misnomer. I actually do have the Lewis labs nutritional yeast. I can't say I love the taste, but both dissolve fairly well in the raw milk, so I don't have issues with the flavor or texture of the lecithin either.
RawZi - the 'never been frozen' part of your recommendation might be a problem. The food I get is mail order from slanker's, and I haven't been able to find something around Northern CA that I can afford to go pick up myself.
Raw egg yolk might help too though, I'll give that a try. I used to drink whole eggs, but I think there must've been something to the idea that there is too much avidin in the whites, because it always started causing problems after a few days.
Just checked wikipedia too, and looks like yuli was right about egg yolks having lecithin as well. Wish I'd known that before buying the soy stuff. I'm not at all a fan of using soy for anything. I think that bottle will be hitting the trash in about 2 minutes.