I had my regular cycle on the 4th of this month, I had unprotected sex on the 11th amd 16th. I started bleeding again on the 19th but it only lasted a couple of days. I again had sex on the 24th and 26th and on both times started spotting, now my stomach is cramping very badly and I am still spotting.

There is absolutely no way to give a medical diagnosis via the internet. If this is a medical concern, see your doctor.