His clinic is located at 121 Brick Kiln Road, on the Billerica/Chelmsford line directly off Route 129, exit 29 off Route 3. It is the same roadway as the UPS office and the Chelmsford Ice Hockey Forum.  The clinic is midway between the two, or at the end of Alpine Street off Boston Road (3A), from North Billerica. Brick Kiln can also be entered from route 3A by Gary's Ice Cream in Chelmsford and the beginning of Plain Street heading into Lowell.  You can't miss it, but many have. Many people are in pain.  The fortunate few find their way to David the Pain Killer.