No, ejaculation does not cause the skin to get darker. Your symptoms are indicative of general health weakness. Yes, it is true many men feel a little exhausted after ejaculation. You need not worry. You should take better care of your health. Even good sleep matters much and adds to better metabolization and assimilation of food and a more energetic body.
You need to go for a "Master health check up" so that you can make a faster recovery. The dark circles
around your eyes and complexion differences are indicating lower haemoglobin
You should visit a General practitioner and have a complete clinical examination. You need some dietary supplements and nutritional drinks.
Do take care of a healthy balanced diet, eat lots of nuts, eggs, dairy products, food rich in minerals and anti-oxidants, Include a lot of legumes, cereals and protein for more energy and better health. You should also drink plenty of water and juices to keep yourself well hydrated. Exercises should be done on a regular basis. Take vitamin B and E supplements. Enjoy good health.