Poor old Rani went to the vet today, who determined that she's suffering from arthritis which is giving her a lot of pain in her lower spine and back legs. Also, some pain in her left shoulder. She's a bit worn out from the trauma of a very detailed examination. So some more meds, but otherwise is in good health. She is 16 soon so a certain amount of this kind of thing is inevitable I suppose.
If the medication doesn't make a difference (anti-inflammatories and stuff), she will have an x-ray and some more investigations in a few weeks to determine what her insides are actually doing.