toy poodle skin discoloration

I have a toy poodle who has just turned 8 years old.  We moved from Northern Michigan to Virginia Beach nine months ago.  Just recently I noticed her normally pink underbelly is turning blotching brown/black all over.  Additionally, she has been licking/chewing near her tail area.  What may be causing this skin discoloration.  -- Thank you!

[Aleda M Cheng, D.V.M., C.V.A]

It sounds as if your dog has developed Atopy (skin allergies).  The new location may have more allergens that your dog is reacting to, and spring allergies are very common.  

Brown/black blotches are probably a dermal yeast infection, called Malassezia.  Please use flea and tick preventative, such as Revolution, because allergic dogs can also be allergic to fleas.

Please take her to the vet for this.  Since allergies can be very difficult to identify to treat and to control.