B complex or zinc both causing me severe fatigue

I posted before about zinc causing fatigue. Now I know for sure it wasn't just the zinc. Its either zinc or B complex that cause it. I was fine this week. On the morning I took the b complex I felt drowsy all day. I could barely function I was so lethargic. Anyone with any knowledge or can direct me to some good reading material about b complex throwing of body biochemistry would be welcome.

Tweet