Rabbit hair doesn't grow very fast. Aki had an operation years ago after which her hindquarter was bandaged during a dozen of days. When the bandages were taken off the fur underneath looked awful, clumpy and with weird spots (her undercoat is white while the hair on the top is dark grey or even black in places so you had a mix of white, greys and black which looked really odd). It took over half a year for her fur to grow back and look normal again. So don't worry, it just takes time! ^^