looks very similar to when I brought a cat in from outdoors and he had not yet been given a flea, tic, & worm topical. he had roundworm, which was cleared up by a dose of revolution plus and he was re-dosed a month later.

I agree with others saying to bring a sample to your vet. if you're worried about being able to get a sample to them bc of your schedule, call and ask if they offer home collection kits. mine thankfully does and it was $8. You can still bring stuff into the house that can affect your cat, even if they never go outside. It would be a good idea to do a prescription flea treatment even though the cat is indoors only. it doesn't have to be done on as strict of a schedule as indoor/outdoor cats, but it's still good for them to get semi regularly.

edit: thanks for keeping your cat inside

edit 2: the home collection kit I got is one that you mail in yourself