Every once in awhile, I would stand up from sitting or laying down and I would lose sight of my vision. I would also get this warm tingling all over my body, I would get a headache and have to hold onto things because I lose my balance. I feel like I'm going to faint, and I just want to figure out what's wrong with me.
This exact thing has been happening to me, I've had them less frequently since I've been increasing my iron intake, you could be low on that! Try taking a daily vitamin or change your diet a bit, you could've been having a hypoglycaemia moment and just need something sugary, check your blood pressure before doing so, otherwise you can throw it off too high
Hope this helped