Damp Brickwall Problem

I have an at grade area (5'x5') of exterior brick that is frequently damp. It seems worse after it rains but it will stay damp days and even weeks without rain. There is a outdoor faucet in the area but I shut it off (shut off is 15' away) and I drained the pipe 6 months ago so it doesn't seem to be that pipe. There is a bathroom a floor above but it is in constant use and the amount of dampness fluctuates.

Any suggestions on what the problem might be and who the right expert might be to look at it (I had one plumber in and he wasn't interested in figuring it out - he said it would be too involved and he didn't have the time or expertise), Plumber? Mason? Basement Waterproofer?