While sexual intercourse my penis does not remain hard for more than 5 min and ejaculation happens very soon what shud I do?

Weak erections? To assess if one's erections have weakened, he should visit a primary doctor, who can check for possible causes: stress, depression, diabetes, high blood pressure, low testosterone, artery disease, high cholesterol, smoking, older age, etc... Causes found can be treated to help make erections stronger, firmer, longer lasting. A urologist can evaluate. Meds like viagra, cialis, or Levitra (vardenafil) may help.