What bulb did you replace it with? Swap bulbs with the one from the side that works and see what happens, you might have the wrong bulb, otherwise there's a short for the taillight portion of the circuitry hat's not present in the brake light circuit.
Has the wiring harness been tampered with back there? Light wiring usually not a issue but if someone has cut into harness to wire trailer hookup that may be letting the gremlins in. Remove light lens see if its all good behind there. I know I have wired trailer lights directly from tail lights
No I checked the harness today and nothing looks out of place, no frayed wires, no holes in the wire jacketing. I do have a hitch but it was put on years ago before I ever had the truck and this light was never been a problem until now. I'm not sure what to do