I don't know anything about elevated calcium levels but the stool issues sounds very familiar to what I was going through with my 9 year old (at the time), Malibu almost a year ago.
We had just transitioned to an all raw diet the previous year and everything was going very well until his stools suddenly became quite mucous-y and awfully foul smelling. I thought for sure that he had parasites and spent several hundred dollars having him tested for various things, trichomonas included. Everything came back negative and my vet was this close to diagnosing him with IBD.
I made one last ditch effort to feed him rabbit only. Literally a balanced diet of raw rabbit meat, rabbit bones and rabbit organs. Stool went completely back to normal. No more mucous and hardly any smell. Turns out, he is intolerant to all poultry (chicken, turkey, duck and especially quail). He eats rabbit, goat and pork with no issues now.
I'm not sure if what your cat is going through is a food intolerance as well, I just wanted to share my experience since the stool symptoms were so similar.
We had just transitioned to an all raw diet the previous year and everything was going very well until his stools suddenly became quite mucous-y and awfully foul smelling. I thought for sure that he had parasites and spent several hundred dollars having him tested for various things, trichomonas included. Everything came back negative and my vet was this close to diagnosing him with IBD.
I made one last ditch effort to feed him rabbit only. Literally a balanced diet of raw rabbit meat, rabbit bones and rabbit organs. Stool went completely back to normal. No more mucous and hardly any smell. Turns out, he is intolerant to all poultry (chicken, turkey, duck and especially quail). He eats rabbit, goat and pork with no issues now.
I'm not sure if what your cat is going through is a food intolerance as well, I just wanted to share my experience since the stool symptoms were so similar.