Often when I work my legs I get lightheaded, dizzy, I'm nearly sick and really need to lay down. This happens mostly if I deadlift, so I never do because of this, but today it also happened when I did a simple leg press and I didn't even do it to failure. This was the first day of gym after a long break, so I tried to take it easy. I pushed myself, but not to failure.

I tried to eat or not eat before gym, tried to have plenty of water or not so much, made sure I breathe properly. Any advice on why this might happen? It ruins my workouts, I just have to go home after resting in my car.

I am a 31 years old male, 192 cm tall and 85 kg and have no health problems as far as I know. Had a blood test a few months ago and had a Vitamin D deficiency and been supplementing since.