Small rashes on Penis red area. Sex?

Hi Doctor, I am sexually active with my partner and we often have sex frequently. Last week i noticed after sex there were few red rashes or small pimple like formation on my penis glans. I am not circumsized. I ignored it since there was no pain for a week. Then again when i had intercourse 2 rashes became red again. Then since 2 days i have put Hydrocortison cream. Now the two rashes does not look red but i can see it there..i have no pain or any other issue with peeing. I am worried if i have sex again those two will become reddish again. Do you advise that i should visit a Dermatologist? Why the rashes come back after sex? I have no pain or itchiness, also during sex...there is no discomfort. Request you to advise