Should I take kitten to the vet?

This morning I noticed that my kitten kept licking her whiskers like how they do after they eat and I thought it was no big deal but she woke up again and she kept doing it and all of a sudden her stomach started jumping and making noise a lot so I rushed her to the litterbox because I thought she was going to throw up and only very little saliva came out and then when she pooped it was very dark almost black with like slime on it (TMI I know) .  She had diarrhea a few days ago so I took her to the vet to fix that issue and after that no more diarrhea but she has been pooping dark ever since.  I get my paycheck until the upcoming Friday so I can't take her to t he vet today. She seems fine but I'm worried that she might be bleeding internally and that is causing her dark stool.

I would, just to make certain all is well.  When they are young like that, their little systems can go out of whack so easily.