Boy do I feel silly!

I think I've figured out why the kitties are getting sick. Saturday night I heard some plastic crinkling in the kitchen, but I ignored it because my kitties often try to pull plastic bags out from under the pantry door. Well, after a lot of crinkling I heard one jump down from the counter and then I heard--crunching? So I went in the kitchen and saw them sharing one of my husband's hot and spicy pork rinds!

In our old apartment they couldn't get on top of the refrigerator, but now they have easy access to it since it's right next to the countertops, and my guess is that they've been eating hot and spicy pork rinds since we've moved in. They should be fine now.

Thanks for all the advice that was offered!