My sister, her roommate and I all possibly have guttate psoriasis..?

[arikas]

My sister recently moved a couple hours away with a friend and her new kitten for college. My sister and her friend are both showing red "droplets" on their skin, my sister all over her torso, and her roommate all over her face. My sister and the kitten came in town to visit, and I couple of days later, I got the same droplets on my chest. My family is friends with a doctor who diagnosed her with guttate psoriasis via images because of my dad's past history with the condition, the doctor assumed it was hereditary.

But I did some research online, and psoriasis isn't contagious, so how did my sister's roommate happen to get the same thing? And how did I get it after my sister came in town? My sister and I never showed symptoms of it as kids, so it's hard to believe it's hereditary. And it's oddly coincidental that I got the same condition two days after my sister came in town.

My sister's new kitten however, has fleas, and she ran under the assumption that it may also have ringworm. My parents don't think ringworm is the case, because then my parents would have the same red spots, and I would primarily have them on my hands and arms, not exclusively on my chest. My dad believes the kitten may have something that could have caused the skin condition, but we don't know what.

My sister has had the skin condition for about a week, and its on a lotion type medication for psoriasis. I just got the marks on my chest this morning, and also used the lotion, which so far has made no difference. I don't know when my sister's roommate got the spots on her face.

Does anyone have any type of idea on what the condition could be?