I would stop calling petsmart for advice... do research online on snake communities like this forum. The reason he had stopped eating before has a few possible reasons common with new owners, but "snake flu" isn't one of them lol.
It's good you're on this forum now! You can read through the stickied threads in the Husbandry section, and also the care sheet.
He's also quite skinny, tiny, and dehydrated looking, on top of his stuck shed, for being over a year old. The size indicates he's being underfed.
I'm sure there are some improvements to be made to his enclosure and bunping humidity to 60%~70% to prevent this from happening again.
get a digital hygrometer like an Acurite to monitor humidity. The round analog ones from persmart don't work.