Faint, lightheaded, dizzy, nausea in head not gi. Have sjogrens/ms etc. No infections. Bp okay. Hydrating/rest. Nausea med help? No new meds. My doc mon

Complicated. Check your BP supine (lying down) and then standing up. If it drops >20 points, it may be the cause of your symptoms which surely sound like low BP to me.
Yes. Whatever you have whether it is from your disease or from vertigo, you will need to relieve the symptoms to be comfortable. You do need to take your nausea medicine and see your doctor in case additional tests or exams are needed.