Dizziness after short period?

Lee
So af came 1 day early last Wednesday and only lasted 3 days! Its usualy 5 days and never been any different. Today I got up and got so dizziness I fell to the floor, luckily I was in mums room so the bed stopped me thumping down lol. Keep feeling dizzy quite often when I get up. Can u still be pregnant after a short period?