My right testicle is more or less always bigger than left and really red since i was diagnosed with orchitis in november 2012. why? something to worry

Testicle size: Testicles are rarely the same size. A very common cause of size difference in testicles is a varicocele (a varicose vein of the 'testicular vein'), which cause less growth in the left testicle. If your testicle is hard, firm, painful, red, or any other concerning symptom, you should see a urologist so that a physical examination can be performed.