You should get checked out. They sound like Mini Strokes and i am speaking from experience. I have since gone blind in one eye.
You need to have someone take a hydrostatic blood pressure of you. Three back to back readings. 1st laying down, 2nd sitting up, 3rd standing up. This will give you a good idea if its blood pressure related, which it probably is and is fairly common. If the pressure drops from reading to reading you could be experiencing a precursor to syncope or may in fact have a syncopal spell in which you faint upon standing.
C'est facile à traiter, mais c'est certainement quelque chose qui vaut la peine d'être vérifié avec votre doc !