hi, i work at a music hall as an usher and part of my job is standing inside during shows to make sure everything’s okay. i have to stand completely still for anywhere from 40-85 minutes straight, and otherwise i’m still standing. recently during shows, i’ve gone through a process where i get faint. first i’ll start to get hot, then i start sweating and getting short breath, my balance gets off, i start getting blurry vision, and tonight i actually ended up getting worsening vision and a ringing noise in my ear. this only happens while working, and i don’t lock my knees. what is this? is it something that i can prevent or should i look for a new job?