Fainting

Your blood pressure may very well have been normal at your check-up but what it sounds like is that you are getting up too fast.  This causes blood to drain downwards rapidly (gravity ya know) and can cause dizziness, fainting, and dim vision.

When you are laying down, try sitting up slowly and then sit for a couple minutes before standing.  Stand slowly and dont move for a min or two to let your blood redistribute itself evenly. 
I can almost guarantee that this will help you. 

I have this problem at times too. For me it is bp related.I went from being on high bp meds to running on the low end of normal now. When I get up too quickly,or if I am on my feet for too long without changing position, I get dizzy,lightheaded,see spots and have to hold onto something. Hope this doesn't ever happen again,how scary for you and your daughter.