Is my cat on its period? I think it might be?

my cat is leaving a reddish/brownish stain on the carpet. It is not poop or anything on it's paws. I started to notice it about a week ago, and it is definitely the cat. She is not "sexually active" and i dont know what it is. On a semi related note are there pads and tampons for cats? If so where can i find them? Can I train her to put them in herself, or will i have to. Thank you sooo much.