Recently (past month or two months) I've been getting lightheaded/dizzy and my heart has been pounding when I stand up, particularly from a lying down position. It doesn't happen every time (e.g. if I've been sitting in a chair with feet on the ground and stand up I'm normally OK, but if I've been lying down and stand up I'll get quite dizzy) but often enough to be worrying and bothersome.
If I stand still for more than about 2 minutes, blood pools in my legs and turns them red/purple and blotchy. After about 5 minutes they get tingly, almost like pins and needles. This can happen in my hands too, but not as bad. My BP does not change, haven't been able to measure HR. It is uncomfortable to stand for very long, and I find myself shifting a lot and leaning on things for support. If I keep standing I can get a hot flash, get dizzy, or feel like I really need to sit down. On top of that I've been really fatigued, and have had bad brain fog/memory/forgetfulness as well as feeling weak and occasionally shaky.
A doctor I saw said that feeling dizzy after standing up and some blood pooling is normal, but I feel like this is outside of normal realms. What do you guys reckon? Should I get a second opinion from another doctor?