What is up with me and all this dizziness?

Hey all, basically its like this: im a really headache-y person to begin with so when these dizzy episodes started I thought nothing of it. This doesn’t happen all the time, but it has been happening increasingly so over the past month or more. The first major one happened when I was standing on the bleachers in my HS gym waiting to take senior class pics, all of the sudden I got a headache and then I got really hot. After a couple of minutes I started to feel really dizzy and I started to get some tunnel vision. I ended up going home w/ a migraine a little bit after that. My second major dizzy spell was this morning. I woke up to the sound of my alarm and I dont know, maybe I got up to fast, but I got really nauseous and then I got dizzy again. I got the whole tunnel vision, then everything’s white and the cotton-y stuffed ears w/ the high pitched ringing so I had to lye down on the floor in order to stay conscious. I got back up a few minutes later and started to head out to school, but I got dizzy again and had to, to my discomfort, lye on the floor of our garage. I plenty of water after that, and after I realized I couldn’t go to school I went back to sleep. I woke up later feeling nauseous again but w/ a slight headache this time (im not prone to being nauseous or getting hot very easily, im typically cold all the time, but when I get dizzy I get really warm). I know this was supper long, but any advice or knowledge as to what this might be? Back in the first grade I had a really bad bout of nausea and migraines that lasted every day for about a month, but we could never find out what was up. could that be happening again? My mom said that if it happened again then I’m going to have to get a whole bunch of tests, which I really dont want to do. I dont like doctors.