Litter Box Problem, Please Help!

Hi, I am new to this forum so please bare with me.
I have a house cat I raised on a bottle from birth. she is 15 years old and never had a problem with her useing a litter box. But all of a sudden she won't use it. I took in another cat that was pregnant she had her own litterbox but got loose one day and used my cat's. the momma and baby have a new home now but my cat has urinated in the box but not pooped. I bought a new litterbox but that has not helped. the thing that makes me think there is something wrong with her is she can be sound to sleep, or just sitting on my lap and she will jump straight up poop in mid air and run like someone shot her. almost like she is in pain. I have found urine and little hard balls everywhere, It seems she goes everywhere that she smells me. My chair and bed most popular. But as she runs thru the house she drops little pellets behind. I went to the local vet and he gave me a laxitive for her but it hasn't helped. here BM is rock hard. Have you ever heard of this and what could it be. I have read about lower bladder infection but does it sound like that. I love Smudge but It is really getting hard to follow her around and clean up after her. Thank You for any help, Sherry

Go to the vet.
Coco gets like that from constipation and bladder infections.
They gave her lax aire for the constipation. She was about 14 when her constipation started.
Your cat is older now so it could be that.

Thanks, I will get her in right away. I'll let you know what happens. Sherry

I think your cat may need an enema at this point. I hope your vet realizes that because if the poop is so hard, it won't come out on its own.

Thanks for the heads up, I will be sure to mention it. Sherry