Kitten puking up food?

I have a 5-7 week old kitten (not sure about her exact age cause I found her). She's tiny, but she's eating canned kitten food. When I first got her last week she was having problems with gunky eyes and a runny nose, so I got some eye wipes and started giving her L-Lysine which was recommended by a friend who's a long-time cat owner. Her eyes and runny nose have gotten better, and she's steadily getting bigger but she's puked three times in the last hour. I don't see anything out of the ordinary, just food. She sleeps a lot, unlike my other kitten (which I found with her) who is rather healthy and playful. I'm scared.