You probably were not paranoid! It sounds like he could have had a bout of gas, which can cause a lot of pain, and can cause body temperature to fluctuate (hence the cold ears). If untreated, gas can lead to GI stasis (and vice versa). You can check to see if his tummy feels firm or is making loud gurgles if you suspect gas.
Others have posted great advice here. Certain foods can trigger gas (especially things in the cabbage family: kale, broccoli, cauliflower, arugula), and since he is so young, he probably shouldn’t be getting veggies at all.
When you do start introducing veggies, start very slowly, with one type at a time (like romaine or carrot tops, for example). Keep track of any bad reactions.
I’m assuming you will separate your buns as other’s have said, but i’m guessing with two it can be hard to tell who is pooping if they are the same size, so it’s important to clean the litter box A LOT if you suspect illness (the same is true when they are housed alone, but it’s a bit easier to keep track).
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.