Skin changing color

Question
I have a daushound, male, will be a year old in August.  He is up to date on all immunizations, has been neutered, and does take monthly heart worm medication.  He has no ticks or fleas on him.  I do use Front Line on him.  His name is Oscar.  Oscar only goes outside to "take care of his business."  Oscar's skin is starting to look bruised, but he has suffered no trauma to cause this.  Our local Vet has no idea what it is.  We recently took him in because he was hit by a car (not run over) but suffered only some blunt trauma injuries.  I showed her the bluish discoloration of his skin at that time and she said it could be hemophelia but then the trauma he received from the car accident didn't cause any bleeding anywhere.  He does have some mild hair loss on these areas.    She said it could be an allergy problem.  I have changed his food to see if that would help.  I did give him some meat tenderizer in his food for about a week a few months ago because he was eating his own poop.  Evidently that worked, because he no longer does that, thank goodness.  Do you have any idea what could be the problem or what might be causing the problem.  

Thanks in advance.

Answer
You should have him tested for tick diseases such as Lyme, Ehrlichia and Rocky Mountain Spotted Fever as well as check as CBC and Platelet count.  Dogs do not normally have bruising on their skin and this could indicate a very serious medical problem.  If all the tests are normal, then you can monitor him.