ive read that over grooming can be boredom related- something to do!
my girl, sparecat is also overgrooming her trousers. she first started when i had kitten sweep as a foster (very dominant little boy despite being about 4months old) then it stopped but the fur hadnt fully grown back but hadnt got any worse for over a year then started again mid dec this year and my poor babes lost a strip about an inch wide a month, shes virtually bald underneath but not sore.
abit easier to deal with at mine because it does roughly coincide with fostering and stopping when i took a break to settle neko in so ive stopped fostering
shes top cat and i think the pressure of having to reassert her position with changing fosters was getting to her. although sparecats been checked and ok for cystitis ive added an extra litter tray as for sparecat, the areas so specific it makes sense that her thoughts might be wee focused when shes overgrooming? shes happy with the extra tray anyway
shes a very happy confident affectionate girl who spends most of her time sprawled across duvets and has good relationships with my 2 boys- they frequently sleep next to each other and neko worships her so i cant think of anything else to stress her!
she was unusually clingy in dec which had me really worried and the vet asked if any young children had recently moved in, as it was school holidays their higher pitched voices could be annoying her- and i did have new neighbours with young children, who are wonderfully quiet, but have the bedroom that shares a wall with mine, which is her preferred daytime nap place and as soon as schools went back she went back to her usual routine, it can be such little things that upset them