low bp can obviously cause low pressure because it reduces the oxygen reaching the brain. Sounds to me like you need to chat with your GP. If I take nitrates to open my
vessels during severe angina, I get stonking headaches for about 3 hours so I know what
it's like. There are certain hormones which control the dilation of arteries but that chemistry is beyond me and I'm sure a GP will be able to give good advice.
just to add, I'm not sure if 110 would give such symptoms, that seems just a bit low. My
wife has 110 as an average but she suffers no headaches or dizziness. However, those
electronic things are usually out by about 10 either way so I would ask a GP to check your BP with a thingie, the stethascope and cuff method. It has a strange name but I can never remember it.