So I got a couple of Bunnies like a month ago and everything has been really great, taking care of them all the time, But like a week ago a problem has been happening to my little male bunny (He’s a dwarf bunny)
One day in the morning I pick him up and turn him around just to find his entire bottom was filled with fresh poop, at first I got scared but I noticed that it’s not diahrrea, It’s just the fact that the poop sticks on his fur alot, and it gets even messier because the shredded aspen also sticks on the poop.
It got to the point that in this morning i woke up and his anus was entirely blocked by semifresh poop and I bathed him (Don’t worry, I just bathed his bottom and dried him well)
Now I’m guessing it has something to do that he always rest lay down and he is still pretty small, But i cant tell for sure.
His bottom is now way cleaner (even tho the fur is painted brown still) But Im really concerned the poop issue will happen again, and I don’t know what’s the reason behind this
Im guessing it has something to do with his fur? (In comparison to the other Bunny his fur is way flufier, almost like if it was cotton) But I cant really tell the real origin of the trouble is and I’m so concerned 
What I feed him is: Water, they have it all the time, Bunny Pellets, and also I bought some Alphalpha cubes which they chew on.
So I would really appreciate if someone could tell me why this happens. 
P.S.: Im sorry if im speaking english really bad, I just hope i got my point through.
BIG EDIT: I just noticed my bunny just pooped and In fact is Dhiarrea
please help me