I sure sympathize about the headache. Those are horrible. The only time I get one is if I have eaten something with MSG in it. And that will do me in for an entire day.
Last week, I ate some beef vegetable soup at a friend's house. It was a potluck. I didn't know that anyone would cook beef for soup with MSG. I was miserable for 2 days.
I don't think I'm alone - most Chinese restaurants advertise no MSG. So I do wish people wouldn't hide it in other dishes.
Ouch! It's true, most people don't use it in everyday cooking. I can't have dairy and didn't think about my boss giving me a cake for my birthday. There was cream cheese in the frosting. :( The next day it was hard to say thank you for the cake, since it made me barf.
Avoid flavoured potato chips and corn snacks then and most prepacked convenience meals they are full of MSG.