This disease is sometimes called black skin disease, coat funk or woolly coat. Although females can have the disease, it is much more common in males.
Here are some great sites that discuss black skin disease:
Before concluding that your dog has Black Skin Disease, you must first rule out: a) thyroid deficiency b) allergies - could be food, environment, flea bites, etc. c) bacterial infection (those black patches could be bacterial infection)
No matter what, you really need to see the vet to find out what you're dealing with.
Let me know if you have questions about anything I have mentioned.