heart broken in shock

two of my n my bfs turtles died yesterday out of the blue, they died right after his bday on sunday, we bought May last year on his bday itself, she was juz 1 yr old, Ai was bought last November on our first anniversary.
it really hits hard, they died together after a long period of not gaining weight and not growing... unexpected but we should have seen it coming...

i suspect they had intestine infection or salmonella bacteria...

we've been going to vets for like... for ever, seen dr vellayan and seen dr jenny too but nothing made much difference... they were eating voraciously actually, juz never absorbing nutrients... the weirdest part is that one was dead with her eyes wide open in stare, like caught in the moment, while the other had her head pointing upward, neck stiff... like it has a shock or something.... weird.... sigh

where can i get timothy hay, bermuda hay, okra and other suitable grass/herbs to feed IST?? i normally shop at the grocery store and i can only get french beans, pak choy, choy sum... regular veggies... want to feed better suitable food to the babies.
thanks :-)
btw: do you feed dry hay or fresh one? i found dry hay for rabbits but my torts won't eat that stuff (i can understand....)
cheers ^^