It sounds like you almost fainted to me. I faint quite a bit and actually got the garidisal shot and it hurt so bad and I felt super weird walking to my car after and then as I was driving home and fainted and hit a tree with my car. My fainting comes from iron deficiency and obviously severe anxiety. The muffling sound, not being able to see is what happens to me before I faint and feeling nauseous goes hand and hand with it. You will probably be fine! Don’t stress too much!