I think my cousin's cat is sick. What should I do?

[petlover001]

I was supposed to go to this party but now I’m stuck at home for the weekend, babysitting my cousin’s cat. I’m pretty sure it wasn’t anything I fed him because I strictly followed my cousin’s instructions and used the cat food from his cupboard. Now he’s vomited twice since he woke up this morning, seems really weak and has been taking a lot more naps than usual. My cousin’s away on one of those multiple city singles tours and idk what to do. Should I take Mr. Wiggles to the vet or wait for my cousin to come back? Help!