Passing out?!

Has anyone ever almost passed out because of really bad sinuses?? The other morning I was getting ready to go to class and I was pretty dizzy but after I got out of the shower I felt weak and nauseous like I was about to pass out. I’ve been struggling w a bad upper respiratory infection. It just really scared me Bc I’ve never felt that way before? I went to the doctor and she just gave me antibiotics and she didn’t seem too worried when I told her I’d been dizzy. I haven’t felt like that since then but has this ever happened to anyone else? What could be some other reasons? Maybe I’m paranoid but it scared me. Thanks in advance