Hi Aisha,
This sure is frustrating. The most important thing to ask is what changed since then – moves, renovations, new family members, visitors, changes outside that may have caused stress or anxiety. Additionally, things to consider might include litter box type, size, litter type, and location. Getting your cat checked out by your vet is also important to check for changes in his health status including organ function and joint health.
All the best.
Dr. Ryan Llera