This happened yesterday to myself and my daughter (both paleo for months). We split a chicken burrito: beans, grilled chicken, a bit of sour cream, tomatoes. She ate the tortilla, I did not. This was from a neighborhood taqueria and we watched them make it. I don't know what oil they used but I'm assuming the basic lard every restaurant uses. The only thing that we ate that was out of our normal diet were the beans.
I haven't had any legumes in months but I can't imagine eating these would cause dizziness. We were very, very tired to the point where I felt like we would fall asleep on the 10 minute drive home. We had no energy the rest of the night and were in a general funk.
I don't know about taquerias, but most restaurants put a surprising amount of sugar in their food. I had to stop going to several Chinese restaurants near where I work because (after a couple months paleo) all their food - meat dishes even - tasted like candy.
Especially if a sauce was involved - even salsa! - it might have too much sugar.
I did miss my favorite taqueria near home - their burritos were so fresh! But one time I was there to pick up a burrito for my wife, and I noticed I could get just the meat as a 'side'. So I got a pint of mixed grilled chicken and beef for something like $6.00 - it was delicious and it lasted for several days of snacks :-)