Are you taking the vitamins on a full stomach? I’ve gotten seriously ill from taking vitamins with no food. Also, hydration is key in proper absorbtion, that could have something to do with it. Your brain is now irritated to some degree and cannot tolerate what it could before.
Many people get migraines from alcohol..hard to believe right?. The clue is it is happening just after drinking..a bad throbbing headache, nausea.
Mostly commoncold causes headache. Accumulated cough creates obstackle in either blood circulation. It can put pressure on the perticular nerve and nerve pain is the worst pain.
Some hard alcohols also have additives now which could be the problem if beer isn’t causing this.

Believe it or not, binging can cause brain damage at a microscopic level. If this really bothers you see your doctor and tell them this.

The obvious answer here is…why do you want to inflict brain damage on yourself? Not to mention the liver..
To rule out allergies or something more serious, I think it would be wise to take your vitamins to your doctor and talk it over with him/her.