Whats wrong with my 9 month old cat?

My cat just threw up about 30mins ago before she threw up she started crying I got cuz i thought she hurt herself then i saw her throw up her breakfast. Now she looks like she lost some weight too. This is the second time she has thrown up within 3 weeks. I didn't see last time but i saw the dry throw up on my rug and there was a hairball. It was all of her kibbles and some spitty stuff mixed in. No she doesnt have rabis I got her 1st round shots but missed the date to get her 2nd shots. She's been a little more lazy as well. She still plays with my kitten but when she's not around she just kinda lays around. Right now she's laying besides me while im on my laptop. What could be wrong.