What's going on with this cat?

She's one of the stray cats out of my house and yesterday she went nuts.All of a sudden she started chasing something invisible(i doubt it was a bug) and her pupils dilated so much!She did that like 3-4 times.Then she attacked another cat for no reason and they started fighting.I'm scared,do you think she has rabies?The thing is that since they're stray ones we don't take them to the vet and stuff,we only feed them and give them water.