What Could Small, Mildly Painful Bruises On The Stomach Mean?

I am 30 years old and my wife noticed small bruises on the sides of my stomach about a month ago. They are still present and more have appeared. The bruises are on the side of my abs and lower ribs. They are only painful when pressure is applies (Like a dull ache). No trama has accured to this area of my body over the past year. Is this something I can wait until Monday to have check out or is it urgent?
What could it possibly be?