PROBLEMS WITH MY CATS!! HELP!!!?

I would check with the vet to be safe but it could be anxiety from any new stressors (ie a stray frequenting your porch, a new pet, or one of its family members leaving). If he is declawed, it is likely that the litter hurts his paws, a common problem in declawed cats, and now he refuses to use it. A third possibility is that it has pain when going due to a UTI or kidney stones, etc and associates that with the litter box. A fourth possibility is that he is old and is getting kitty alzheimer's, forgetting where the litter box is. This happened to my cat. You can try removing all stressors and using a special cat-attract litter. Look at your cats' behavior to try and determine the reason behind it. If he is pooping by the box but not in it, then he knows where it is and it is some kind of pain or avoidance of the box causing the issue. If he is going all over the house, it is more likely stress or kitty Alzheimer's. If he goes in the same spot in the house that is not the litter box, then he went there one and it now smells like a place where he thinks he should use the bathroom - clean it and put orange-scented sprays there. Good luck, and it is always best to seek help from a vet!