Why after i ejaculated then pee i have a burning sensation in my penis?

Prostate swells: With sexual excitement the Prostate swells in preparation for ejaculation. After ejaculation the gland needs probably 15 20 min to begin to go down. This is when it would hurt a little to pee. Some just cannot pee for 30 plus minutes after sex. It is very normal

Spermicide? Soap?: I wonder whether something irritating is getting into your urethra. Common offenders are spermicides, either by themselves or in condoms; and soap, e.g. after masturbating with soap as a lubricant. If you avoid those things and the symptom continues, or if you also have discahrge of pus or mucus from your penis, see a doctor for an STD checkup. Good luck.