I had my lap band done 11/12/15. What type of issues cause severe port pain one month post op?

I agree with the other comment below with regard to seeking a doctors attention, ideally the surgeon who put in your lap band.  One possible cause of an infection in the port are beyond the immediate postoperative period could be an erosion of the band into your stomach.  That would allow fluid from within the stomach to exit and track along the tubing, collecting in the pocket where the port was placed.  Alternatively, you could have an incisional hernia.  If the port was placed over top of the muscles which were cut at the time so the band could be introduced into the abdominal cavity, it's possible that the separated muscles did not heal completely, or a stitch that was holding them together ripped.  This could allow something like a hunk of fat from inside your abdomen or even a few inches of your intestine to get pushed through that opening and be experienced as pain and swelling in the area of the port directly under the skin.  With regard to the second part of the comment below, I do not agree that the lap band is a bad operation with a high failure rate.  In general, beware of all or nothing statements.  The lap band has a proven track record to help most people lose weight and keep a large percentage of it off durably.  Follow up and a commitment to exercise are keys to superior outcomes with the lap band, but in my experience when placed in appropriately selected and well-counseled patients the vast majority lose a significant amount of weight AND are happy with their decision.  

You should call your doctor or go to the emergency room.  Despite your saying that the incision looks fine, it could still be some kind of infection.Note to anybody else who may be reading this:  please do some research before getting a LapBAND.  It's a bad operation with a high failure rate.