Today after having sex with my boyfriend, i noticed in his semen there was a hard, dark brown lump. his semen is a clearish yellow colour and the lump was approximately 5mm x 5mm in size so it was rather obvious. I've been with him for a while now and never noticed this before. he has a very low sex drive and often can't ejaculate. he is 19yrs old. i haven't talked to him about it, as he is the type to stress, and i dont want to worry him if there is nothing wrong, so i'm not sure if he has experienced this before... please tell me is this normal? ive searched the internet and cannot find any answers.