I would recommend consulting your PCP/Family Physician for labs and possibly imaging of your head.
it could be your blood pressure,or your iron might be low,go to the doctors for blood tests
I don't think it means your weak. I don't know I'm not a doctor but from my experiance since I get lighte heade alot and have researched it. It has to do with standing up to fast and your blood pressure momentarly dropping. So the oxegen is not able to get up to your brain. Though this is considering that you feel light headed when you stand up??? I know even today I stood up to fast durin my bath and I think I fainted because I don't remember falling I just remember ending up on the floor and hearig the towl pole thingy hit the floor cuz I had neem holding onto it and when I fell I accedently pulled it right out of the wall. Though I'm not sure if I fainted or not. Though my head has felt weird all day since! Does any of this sound familiar???
this is not good,tht means you are very weak, i would tell to see a doctor may be he or she will prescribe you some good medicine.