Pregnant cat?

My cat has been acting really strange lately, she's been meowing constantly, and will not leave me alone. She also keeps acting like she's in pain, and will be resting and all of the sudden jump up, cry, and run out of the room. Her belly has gotten huge, too. Does this mean she's pregnant or is she sick? Thanks.

If the cat seems to be in pain, you should take her to a vet. From the behavior, it's possible that the cat is in heat. But, there could be something wrong with the cat.

How old is the cat? Have you considered having her spayed (which would get rid of heats, and would prevent an unwanted litter)?

.....worms can nalso cause the stomach to swell.

I definately think a visit to the VET is in order to have her checked.