I have been having a fever every time I have sex or ejaculate. I am a 24 year old guy and I ejaculate 5-10 times a week, making me feel dizzy, tired and sometimes a fever sets in.
"Whoever commits adultery with a woman lacks understanding; he who does so destroys his own soul. Wounds and dishonor he will get, and his reproach will not be wiped away" (Proverbs 6:32-33).
The most common cause is an infection in your prostate gland. Since you are having promiscuous sex, it is likely you picked up the infection from someone else. You need to see your doctor to get some antibiotics.
Another possibility, though not nearly as common, is being dehydrated.