My baby kitten has diarrhea, what to do?

Found a lost or abandoned kitten (maybe 5-7 weeks old), so starved that I could feel all of his bones right under his skin and his face was very hollow. Took him home, he is eating and drinking, (purina kitty food, water and a little of canned cat food per day- I want him to gain some weight). today was his second day with us, but his diarrhea is not getting better, a little better in color but not much in consistency. Yesterday it was dark green and there were dead leaves and tree seed husks etc. in it. Today I found what looked like maybe a little blood. He was doing much better though and was even playing, yesterday he just wanted to be held like a baby. He is so sweet, we are totally in love with him but can't commit to a vet visit just yet. What do we do? any ideas? also should we try to bottle feed him?