sealpoint turning ginger and fur not growing back

by Claire
(Auckland, New Zealand)

My 6 year old sealpoint siamese has started turning ginger! In the past when stressed she's gone grey arround her eyes and mask but this ginger is all over and now starting to affect her mask. She also has an area on her leg where she was shaved that hasn't grown back in 18 months. The vet said it could indicated hypothyroidism but blood tests were negative. Any ideas?