Knee pain- Second Opinion?

Patient: Hello, I am a 18 yr.old female and for a few years now I have been having knee pain, particularly in left knee. I went to a doctor and he said 90% chance Paletofemoral Syndrome but I am not satisfied.and would like a second opinion. Most.of the pain is in the upper.left kneecap on the left knee. It is like a hard roundish bump that hurts even if.touched.slightly… feels a a bruise but worse!! Any ideas?! Your greatly appreciated :)The pain becomes worse when bending excessivly and I find it difficlt to walk!

Symptoms: Pain in knee