What breed of dog is he?Is there anything new in his environment (new carpet, furniture, new laundry detergent, ect.)?Has he always done this tearing, or is it new?Does he chew at his feet?
He is a Bullmastiff
The Tearing is new but nothing has changed in his environment.
He dosen't chew at his feet but he does lick them alot.
It sounds to me like you may have an allergy dog on your hands. A couple of common signs of allergies is the tear staining and the licking/chewing at their feet.
Something you could try would be some Benadryl. The usual dose is 1-2mg per pound once every 12 hours, so if your boy weighs 100 pounds, he could have 4 of the 25mg tablets once every 12 hours or so.
You might also want to talk to your vet about trying something a little more standard to control the allergies. Medications like Temaril P or Atopica are made specifically for allergy dogs and really do keep them in check.