So a little under a month ago I bought 2 kittens. Rambo & Simba, they're brothers. Rambo has no problem using the litter box(es) (I have 3) and he's what you'd expect from a kitten: playful, cuddly and super energetic.
While Simba is also all 3 of those, he has some troubles using the litter box. I have 2 litter boxes in the bathroom each placed in different spots, and I've moved each from place to place in the bathroom. Rambo has no issue with this and continues to use them no matter where I put them, but Simba, however, only -sometimes- does his duty in the litter box.
I can not count the times he's done his business in the corner of the shower or on the hard floor on the balcony. He seems to do it in "hidden"ish spots. The strange part however is that he has used the litter boxes many times before, so it's not like he doesn't know where they are or how to use them. Granted he doesn't cover up his poop or pee, but I don't mind that too much as long as he'd continue using the boxes.
Whenever I've caught him getting ready to go poo in the corner or on the floor, I've gently picked him up and put him in the box and even dug at the sand with my own hands in an attempt to demonstrate how to dig a hole and encourage the use of it.
Of course he then does his duty in the box after I've put him in there, and I praise him for it, but I can almost certainly expect him not to do it afterwards, as he resorts to doing his doodoo's on the balcony floor or in the corner of the shower.
I've put food bowls on the balcony and shower floor with some food in them, of course, but he just decided to poop beside them.
Now for a strange part: he only poops a little in the box and poops the rest outside of the box.
His brother is not antagonizing him or anything, and I've made sure to let Simba do his business in peace whenever I catch him actually going to the litter box himself.
It's not a matter of cleanliness, as I clean all boxes 3 times a day and the litter is supposedly meant for kittens. It's the "Ever Clean" brand. The previous owner used wood pellets but Simba would still not use it frequently as I noticed when I went to pick the kittens up; Simba went and did his doodoo's in the corner of their apartment in front of everybody.
I simply assumed that the small kitten was stressed that so many strangers suddenly barged into his home and he just got so riled up and didn't have any time to hold back his urge.
Well here I am now with a kitten who doesn't take the hint.
It saddens me because I can't keep living with a kitten that poops everywhere except where he is meant to, because my own apartment starts smelling absolutely horrible.
He's currently on antibiotics and 2 other "medicines" that should help in case there's something wrong with his bowels which discourages him from using the box frequently, but I've seen no change in his behaviour so far. He's been on the meds for about a week.
Sorry for the long post. Hopefully you can endure through it and give me some well needed advice here.