i recently tried some simple meditation exercises but in a diffrent posision

instead of crossing my legs
this is hard to explain standing with your knees bent while leaning on your toes

i tried this because i use this position a lot and in the beginning it hurts if you do it too long

but when i stood up and opened my eyes i saw the area i was in (my room) and then
i couldn`t see anything but black for a second and everytime i do this it happens again

so is it normal that you cant see for a second and feel something in your head after meditating(like when your standing upside down)?

It is a drop in blood pressure due to sitting in one position to long, then suddenly rising.

It's blood pressure for sure.

If you move a couch from the wall, lay over it with your bellie on the top of the backrest and you head over the back making sure your head is under hip hight, get up too quick and you see black or faint.

Use to do it for kicks as a kid :]