Why do i randomly bleed after sexual intercourse and the blood smells like the last of my period? i have no irritation though

Yes: This is not normal--at any age. Get this looked at and worked up ASAP. Of course, there are many possibilities. My primary concern would be to rule out any growth/cancers and/or pre-cancerous changes. Such changes can occur anywhere along the reproductive tract (e.g. vagina, cervix, uterus, etc..). As such, a thorough evaluation is warranted.