I dont know. But worried

I am 20 years old and in very healthy condition.  Over the past few months i have been having some pain in my testicles, not a very strong pain but i do get noticable aches(i'm pretty sure they are not in my head).  I got STD tested earlier this week for HIV, Gonorrhea, and Syphilis and my results came back negative.  The past few days my left testicle will all of a sudden turn a darker more purple color and move up towards my body while my right one stays the same causing an unusual feeling.  I usually stretch it out and it seems to let the bloodflow back in and it drops back down, but it reoccurs frequently throughout the day.  Its making me paranoid.  Could this be a sign of testicular cancer? The pain does not seem strong enough to be a testicular torsion. I have been everywhere online searching the symptoms and I cant find anything.  I have a doctors appointment in 3 days but i need to try to ease my mind somehow thats why i am on here.

[alek]

well i guess this site is helpless..