Little Marco is sick. :(

My little gray kitty (Marco) is sick.
Since they both came home with me, they have both had diarrhea, the brown one (Chris) and the gray one (Marco). My mother thought it was because of the de-worming stuff the guy gave them right before they ame with me. My grandmoter thinks it's te change in their food, since we didn't ask what food he was feeding them. But today Marco has been having diarrhea and vomited once today. And not too long ago he went to the litter box, and it had a little red in it's waste.
I told my mother about all of this, so we are going to take them to the vet's in the morning.
I hope little Marco and little Chris will be all right. I don't want to loose my new kitties after just loosing Margret, and having just got them.
sarah R