do you have a fixed flow shunt or a programmable? do you know if you have a anti-siphon device (some shunts have them builtin, other times one can add then to the configuration). there are a variety of causes for headaches - our child gets them from over draining so traditionally such headaches show up later in the day and are improved by lying down (under draining can cause headaches also, then you may need to sleep very propped up which we've seen long ago). so the over draining can get worse so that headache is constant- adjusting the valve to a higher setting completely fixes it or if it only helps, we adjust it higher.

early on when we saw under draining (strata didn't go low enough either, very low pressure), our surgeon replaced the valve with built in anti siphon to a system without and our child did exceptionally well.. until her pressures started going up. so after adjusting her up, eventually we saw that didn't help so the first thing was to add an anti siphon back into her system, that helped for a while and we could adjust her up on that system for a while ok until eventually that wasn't enough so the system was upgraded to two valves in series and we kept adjusting her up until the top setting wasn't enough, got a stronger system and are going through the routine of adjusting that up... about to ask about a cmvp system.

most people do well just with adding an antisiphon if they are missing it or adjusting the valve setting (equivalent for fixed flow is replacing the valve with different vavle).