I have the same problem and have been advised to do two things. I’m not a doctor so trying this is up to you. The first is drink a ton of water. If your BP is low, drinking a couple bottles of water increases your blood volume and ups your BP. The second is add more salt to your diet. This goes against all the advice I’ve ever heard but it has helped me. And be careful with the water. Don’t do the massive drinking more than once a day. You can get sick from too much water. Just keep up a steady stream.