I had my second allergy shot for dust mites on Saturday, and about 30 minutes later I took some Mucinex.

20 minutes after that, I developed a throbbing headache, which was "global" (all over the place). It lasted for about 2 hours.

It didn't feel like my typical allergy headaches, which tend to be localized behind the ears or above the eyes.

I'm trying to figure out if this was from the allergy shot or the Mucinex.

Anyone have anything like this happen?