Q. Why does the color of semen differ?

Hi doctor,

I am a 25 year old male. I have been dealing with erectile dysfunction for nearly three years now. My sex drives do come and go, but it is based on the quality of my semen comes out. Sometimes, I have a good sex drive along with a good hard and my semen will come out rich white and a normal amount of it. But, those days when I have trouble in getting hard on along with low sex drive semen comes out with a little tint of yellow. Also, my penis is not fully hard, not as sensitive and aroused. I have dealt with anxiety, but later I have been fine. But, this problem is not getting much better nor getting worse. This problem started three years ago. In the past one year, I am also getting some throbbing pains in the vas deferens. I am not too sure of the area, because it is hard to pinpoint. I feel a pain from the bottom near my testicles to my abdomen and sometimes slight pain in the prostate area. It is a pain that I can feel enough to dismiss it and move on. I know I should get checked. But, first, I would like to get an opinion from a doctor. Thank you.