Sometimes, when I lay on my back outside and l stare straight up at the sky for a long time, I feel really disoriented, weird, and afraid. I feel like I am floating in space and also like I am falling towards the sky at a great rate of speed. It sorta feels like a roller coaster ride but much worse. Then I start to feel as small as an ant and expect to see a giant! Has anyone else felt like this? [No. I don't do drugs.]

You also said that you feel like your 'falling' into the sky? Maybe you also feel like you can't hold onto anything, and that the sky could just pull you into it? It could be panic as well, as panic attacks can make your vision distorted and make you feel disorientated.
Anyways I think it's weird but I would say it's no big deal . Lol