Testicle Lump

Im 19, and right now I have a hard lump (or ball)connected to the bottom of my left testicle.  When it is squeezed, I don't have any pain, nor can I feel that is being squeezed.
At first, it started as a sore spot, that ached. There was a lot of fluid, and my testicles seemed to droop more and they felt quite heavy.  I soaked in a warm bath, and that seemed to help the swelling and aching go away (or holding an ice pack to it for about 20-30 minuted), but it would come back.  After about a week the swelling and aching went away.  I started noticing a lump forming and it is completely painless now.  There is no soreness, aching, and my left testicle is not swollen anymore.  It worries me, and I don't want to completely assume it's testicular cancer.  But I'd like to know if maybe there are other options of what this could be.