Why does my knee still hurt?!?

It has been since October of 2010 when my orthopedic doctor said I had runners knee in my left knee. I havn't ran since the end of october because I was not suppose to. My knee kills! Everyday it hurts. If its not swelled up a little, then it is alot. My mom refuses to get an MRI done but the doctor says I should get one. I did the excercises they told me to do and that just made it hurt worse. Any advice on what to do? Anyone think they know whats wrong? Also I'm going to Myrtle Beach tomorrow for a week so how am I going to deal with the pain all week from walking so much?