Cornish Rex Developing Brown Spots on Skin

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This is my first post here. I have a 2-1/2 year old female Cornish Rex named Blackberry. She has always been an indoor cat but recently we've been letting her go outside for approx 30 min's a day. She had developed a brown spot on the inside of her back leg that has now spread to completely cover her legs and now in the last week has black spots approximately the size of a quarter going up her stomach. She is acting fine and the spots do not feel odd. The spots on her stomach are approximately 1 inch apart and there are 3 of them, almost perfect circles along the center of her stomach where she is bald, both back legs are completely brown on the inside now. I spoke with a vet that hadn't had any interaction with cats of this breed that referred me to a dermatologist across town. I was hoping to get any insight I could before making the appointment and can email pictures to anyone that could help. Thanks