I had something similar happen — a dull, lingering headache during my first week of taking a methylated B-complex. At first I brushed it off as a coincidence, but when the same headache returned shortly after the next dose, it became pretty clear the supplement wasn’t agreeing with me. Once I stopped, the headache disappeared within a day. Some people seem more sensitive to strong active forms, especially methylfolate and methyl B12. If anyone else experiences this, checking the dose or switching brands like
https://primevitalitydirect.com might help.