Then no, headaches should generally not get worse except after the first couple of weeks at a new dose. But then generally is the operative word. Maybe Nori isn’t the cause. Doctors consider a med (any med, device, etc) successful if it reduces symptoms 50% of the time. The rest of the time we suffer and occasionally take rescue meds, exercise or do whatever our favorite strategies for beating it back down again happen to be. (For example, I’ve got a splitter because I had my messed up neck worked on today. I’m going swimming. If that doesn’t work, I’ll try something else.)
It’s one of the reasons we talk about 80-95% better as a success story. Most of us have some symptoms some or all of the time. It’s a matter of intensity. MAV isn’t something that can be cured so much as managed. Look at your diet and other triggers over the last few days. Too much salt? Nitrates? Artificial lighting? Stress? Got a cold? Or maybe it’s just random. If you are generally trending worse over weeks or a month, then look at augmenting or switching up meds. It has to be viewed as an average over time. Keep a diary for your neurologist. If it’s been a month, it’s time to go back in.