Blood pressure is an interesting thing hey?
In your case, where you are seeing symptoms of low blood pressure that are effecting your day to day, I think it’s worth looking into ways to help keep it on the higher end of low. 😉
So in terms of some ideas of what you could try for this:
1: As you have already mentioned, hydration! This can be one of the best ways to keep it up there. If drinking water isn’t working as well as you hoped, try adding some electrolyte supplements every once and a while (especially when you have been working out, during menstruation or even just feeling more lightheaded, etc.). There are also trace mineral drops that you can add daily to your water for maintenance of minerals (needed for proper adrenal and thyroid and cardiovascular function – I mean everything really!)
2. Get your iron (and hemoglobin!) levels checked out. This is another potential cause for your lower blood pressure along with the intensified symptoms (dizziness, faint, foggy head, etc.) Both 1 & 2, play into the menstruation situation. Many people experience blood pressure low enough to cause some unwanted feelings and often it comes back to getting enough electrolytes, magnesium and iron, since the loss through menstruation can be significant.
3. Keep that exercise going as you mentioned, but always make sure to properly and fully hydrate/re-hydrate.
4. The herbs: Hawthorn would actually be okay for you to take. Use a mix but with a bit more berry than the flowers/leaf. Hawthorn seems to help regulate rather than just bring BP down. Keep an eye on it, but it generally is not a concern unless someone is taking it along BP lowering medication alongside hawthorn.
You could try using licorice for the short term, especially if you feel there may be some adrenal connection, but that is not the best option for long term results.
Otherwise, as you mentioned cayenne would be good on occasion, gotu kola could be of some nice support and I also really like rosemary for hypotensive or depleted situations.
Ultimately, start with building up blood, nourishing and toning. This will support you from the core.
I hope this is some use to you and that it gives you some ideas/solidifies what you were already thinking/knowing to move forward with!