I've been having pain at the base of my left index finger on the side of my knuckle after I changed my 2HBH grip. It seems like whenever I hit a backhand, this part of my hand knocks against the handle of the racquet. It was just a little painful, like I hit a nerve but it is now visibly swollen compared to the same part of my right hand. Has anyone experienced this before? What can I do other than change my grip?