My dog got a parvo shot and a rabies shot on his first visit and now he is sick what does this mean?

he will not eat and we give him chicken broth and gatorraid to keep him hydrated and pepto for his sad little tummy but the reason we took him to the vet is because he swallowed a string and he was having trouble ping it so the vet pulled it out and he said he might have more so we gave him something kinda like mineral oil so he would poop bc he hadn't in awhile now he has dighrea so what do you think do you think it is parvo he is wanting to sleep but then he will get up and eat alittle and play other than that we have to feed him with a surring and he will not eat solid foods could it be parvo or could it be from the string upsetting the his tummuy