What Causes Spotting After Sex And Light Periods?

hi my name is angel i am 19 years old and i have a gyno problem bn, i started bleeding very lightly directly after sex and bled for the next couple of days on and off but my period was scheduled and i thought maybe the hormones while having sex might have brought it on. this was last month, this month i have not been having sex for i thought i had an bacteria infection and my period came for three days and was extremely light unusually, light but it was on schedule what does this mean?