What kind of worms does my cat have?

I have 5 indoor cats, and one of them got out on the roof through an open window. A couple of weeks later I saw worms coming from her butt. They were coming out wiggling, and they were about the size of pieces of rice. They are a yellowish/white color. Later that same day I found the same worms in my own bowel movement. I went to the doctor, they took blood and a stool sample and said that the worms had passed and were no longer in my system. For a while we didn't see worms on the cat either, but just saw them again the other day. I am fine this time so far. What kind of worms does this sound like? I can't afford all the vet visits again! I researched it online and it sounded like roundworms.