Ok, so yesterday my dog threw up 3 times.

First it was greenish goo then I believe when most everything had left his stomach it was more greenish/white foamy. He has also been pooping a lot and not eating.
Last night I awoke to find two spots of greenish/foamy puke on the rug and two spots of thick brownish stuff. One rather large and one tiny spot. My first thought was he puked blood but on closer examination it was very watery and came out brownish/green on the paper towel. (no red) However...if it isn't blood I don't know what it could be. (I am no expert by far)
This morning he has been having extreme liquid diarrhea outside. Not sure if this was also happening yesterday or not but it is likely. So..maybe last nights pools of brown blood were actually diarrhea?
Any advice on this? He hasn't eaten but does drink some water. He does not seem to be in pain but does seem a bit lethargic and shaky. He has not eaten anything to my knowledge out of the ordinary and he just had a vet check-up last week. (it is possible he ate something in the yard without my knowledge) He is an 11 year old Shi Tzu mix.
Thanks!