Pain in Testicle and my spermatic cord is little swollen

2 yrs back I suddenly, overnight, had a swollen left testicle, I met a doctor and he said it may be fileria and it will be ok soon(but it did\'nt happen). Now, I am feeling pain in my left testicle,lower abdomen till thighs regularly. My left testicles sometimes becomes hard, and, I can see it shrinking significantly as compared to my right testicle and my spermatic cord is little swollen. I met an urologist but he said its normal. I did ultra-sound that showed its not varicocele and there was a normal study. I am not understanding what is happening and I am not getting the reason for this pain.plz help I am very tensed.