What kind of treatment options are there for those with low blood pressure?
Yes, there are medications that are good for raising blood pressure. Two specific medications I can think of and have used are Florinef and Midodrine. However, these should be used with caution, as they have some side effects and the blood pressure should be monitored carefully while using these types of medications.
As for your mother's headaches, I hope that she has been seen by a neurologist. Many of them specialize in headaches and may help your mother with her pain.
Maybe your mother has a histamine intolerance. Check http://histamine-intolerance.info/