Looking through a listing of the Air Force Aircraft inventory for the P-38's. They were stationed at the following locations in Belgium, the letter and number after the name are what the military likes to do, the give names to things as they start operating out of them, makes it easier to say the names.
St-Trond Airfield (A-92)
Le Culot Airfield (A-86)
Asch Airfield (Y-29)
Florennes Air Base
If you could see the serial number of the plane in the photo the inventory could tell you more information about the plane.
Dean