I am glad to hear that other than the change in the color of your semen you otherwise are feeling well. However, I would still suggest that you make an appointment with your primary care doctor
to discuss this issue, especially if the discoloration persists.
Some variation in the color and consistency of the semen can be normal, especially as we age. However, since this is a new change for you, it needs to be evaluated.
In particular, there are a few medical conditions that can change the color of the semen. One of these is a prostate infection, which tends to give the semen a darker yellowish color. Other symptoms of a prostate infection might include burning or discomfort with urination or with sexual activity. The other is blood in the semen, which could be caused by a number of things irritating the prostate, once again including infection but also, occasionally, a sign of a tumor in the prostate.
Your primary care doctor will be able to perform a complete examination, including looking for any swelling, tenderness, or lumps inside the prostate that might require further testing. If there is any evidence of infection, that should be treatable with standard antibiotics. Please see your doctor soon.