Low blood pressure

Kaylina • Twin girls born 3/3
Hi ladies,
​Lately I've been feeling crummy. Dizzy and nauseous at times and my headaches are back (from earlier in pregnancy).  Went to the doc on Wednesday and she said it could be caused by my low blood pressure (80/40), which was fine at my last checkup 2 weeks ago. Anyone else? Has anything helped? Doc said to eat more salt and drink more water but neither seems to help so far!