My 10 yo Serengeti is silver with black stripes. The other day I noticed a dark brown patch. It is not painful, and his skin is not discolored-it's only the fur. The area doesn't bother him at all when touched. I will try and attach a photo. I have no idea what could've caused this, and it must've happened quickly because I pet and give him back scratches every day and inspect him. Perhaps it didn't happen overnight, but I definitely don't think it took long to develop. Has anyone dealt with anything like this? I know older cats can get gray, but this is a rust/brown colored spot. Thanks for any help!