It does.
Glutamate is found in many foods. So while you might have gotten a headache, it was probably from something else. Perhaps from all the added salt in general. Zizzi, Nandos and KFC all use it, along with almost every food place.
Everyone in Asia eats way more MSG than people in the West consume in a lifetime, yet they don't seem to have MSG issues. And they have been eating it for much longer.
For instance:
Some of the names MSG goes under in the UK:
monopotassium glutamate
glutavene
glutacyl
glutamic acid
autolyzed yeast extract
calcium caseinate
sodium caseinate
E621 (E620-625 are all glutamates)
Ajinomoto, Ac'cent
Gourmet Powder
The following may also contain MSG natural flavours or seasonings
natural beef or chicken flavouring
hydrolyzed milk or plant protein
textured protein
seasonings
soy sauce
bouillon
broth
spices
Almost every flavour of crisp here, except for ready salted, has MSG.