i started taking testosterone injection to bring my testosterone levels to normal 21 year old male levels. over the past week my sex drive seems to have gone down and dont ejaculate right. befor i could shoot but now it does not shoot. should i call my doctor about this?

I have read that it can shrink the testicles and make them useless. My friend is on Testim and it is increasing his testosterone levels, but he is only 30 and concerned about his fertility.