Take I-95 North to Exit 23 toward Route 146 North/Woonsocket.
Follow 146N for approximately 9 miles.
Immediately following the Route 116 South exit, there will be an exit for Route 99 North.
After passing the exits for both I-295 North and South, you will see the split for Route 99.
Follow all signs that bear toward Woonsocket.
Follow Route 99 until it ends, which will be at the intersection of Route 122.
Turn left onto Route 122.
Continue on until you have passed through four sets of lights.
At the fifth set of lights (Dunkin' Donuts will be on your right), bear right onto Cass Avenue.
Ocean State Pain is on the right, located in the building next door to the Landmark Medical Center's emergency room. Parking is in the back.