I'm so sorry Bri, my thoughts are with you. RIP sweet ButterBear, your little life did bring joy to Briana's and you will be sorely missed.

It sounds like he had wet tail, which is contagious. I'd keep an eye on Dipstick and if you suspect anything get him to the vet immediately. Wet tail is a killer but if it's spotted within 24 hours it can sometimes be curable. I would move him to another cage or give the cage a thorough scrubbing with strong disinfectant. I really hope Dipstick will be OK and keep strong Bri.