Dizziness

Was wondering if anyone on here would have an idea as to what it is I'm experiencing. So months back, about 6, I would get this dizzy/ lightheaded feeling, it was bad, I couldn't tell if I was walking straight, vision would blur, nauseated, and sometimes a headache, my pupils would be super dilated, i felt like I was going to pass out . I would space out and not really realize it. Everything would seem so fuzzy, and I couldn't remember much after the fit was over, over time the fit would last all day long. I went to the doctor and they ran some tests, but couldn't find anything wrong, made sure I was hydrated, gave me 2 pills for dizziness and sent me on my way. Well over time it kind of just disappeared, but recently I noticed its starting to happen again. It sucks. I just wanted to hear what others thought. Thanks.