I recently noticed (yesterday) my semen changed colors. it is now a bright yellow. this has never happened before. i have no pain when urinating or ejaculating. there are no abnormal odors. there is no discomfort whatsoever. ive been with only one partne

Seminal vesiculitis?: Yellow semen can mean seminal vesiculiitis, i.e. inflammation or infection in the seminal vesicles (where semen accumulates before ejaculation). Often it clears on its own -- no worries if your semen returns to normal appearance over the next few ejaculations. If it doesn't change, see a doctor, ideally a urologist. STDs have not been associated with this symptom; no worries on that account.