Sorry to hear Ruger threw up, but glad he is doing well with energy and eating.
Grass eating seems to be a Yorkie thing. I originally thought dogs only ate grass to try to throw up or to settle their stomachs, but I've read so many comments here about Yorkies pretending they are sheep and munching on the green stuff. My boys both grab blades of grass and weeds on their walks. In fact, a very, very long piece of dried grass came out of Teddy today.
If this is a new thing for Ruger, then it is more concerning.
You mentioned in your other thread that he was eating a couple cherries for treats at night. I would hold the cherries, if you aren't already. They can be irritants to the digestive track. Teddy had a very sensitive system when he was younger and could handle only a very limited set of fresh food treats. He still doesn't do well with fruits.