My dwarf hamster named Remi is almost 3 years of age, I'm very grateful for him living so long but I noticed two days ago his tail looks wet and he has very soft poop/diarrhea but I don't think it is wet tail because he is still pretty active. I have had a hamster in the past with wet tail, he sadly died but before he died he was sluggish and didn't move much and just stayed inside his nest; Remi doesn't do this, but he still roams around often.
I've noticed he goes to his food bowl more often, I could have perfect timing but it is a bit of a concern for me. I haven't replenished his food for 2 days now because his cheeks are almost always full when I see him. I did give him a small boredom breaker with food in it just in case he is bored; I see him lying around in weird places instead of inside his houses, is that normal? I might do a spot cleaning later today if he has dirty spots around his cage. His cage is pretty big, not like anything you buy from pet stores, so I don't think this has anything to do with the amount of space he has.
I'm not sure what to do and I could use some tips from people who have had hamsters before, preferably Russian dwarf hamsters but any tips are welcome.
Update: Remi sadly passed away overnight, he lived a long good life. I will miss him.
Summer Month: 3 
Night 
Clear Moon: 
