My left testicle is twice as big (almost size of palm) than the right. Should I be worried?

I know this is normal for men to have different sized testicles.
But I noticed at an early age that my left testicle was slightly bigger.
I just came to notice recently that my left testicle is LARGE, almost the size of my palm, whereas, my right is 'tiny' (in comparison)
My left testicle pains slightly (recently) and I have no idea why. All I have been doing (recently) is lifting weights.
I am now 21 years old. This is freaking me out! No lumps so it won't be cancer. Or is it?
Awaiting answers.
What should I do? Should I be worried?
I have not masturbated for a while now.
And on further 'exploration' of my testicles. I think my left one is swollen and not really abnormally enlarged. I live on my own, and a doctor is just (expensive?)...I am looking for helpful answers, and if this will go away or how serious this is, and if anyone else had this.
Thank you all.