8 week old black lab with parvo please help?

i have a 8 week old black lab and i took him into the vet on monday and they said he tested positive for parvo. He started getting sick on saterday where he started throwing up and having diarrhea he stopped wanting to eat or drink on his own and dident want to play anymore..he was sick like that all the way intell monday (the day of the vet visit) then he started getting better on tuesday where he would want to play with me and eat and drink a little on his own then wesday he was eating a lot more and drinking on his own and today he is still eating a lot and drinking hes been wanting to play all the time and he is acting like he is all better...ive been giving him pedalyte every 30 minets since saterday and the i.v flids the vet gave me..i also have a 18 week old sheltie puppie who has been away from the sick puppie my question is when can i bring the lab out awround the sheltie? the lab is acting just fine..how do i know when he really doesnt have parvo anymore..my lab crys at the door and wants to come out to play and i feel that its not right to keep him in his rooom all day if he is better..please help