Is it possible to get a your period after 2 weeks of already having what you thought was your period?

Since my Mirena after the birth of my son in 2012 (the 5 yr).......So on 5/14 I had what spotting;darkish brown and following very tiny bright red spotting on 5/16 till 5/18. Nothing major, this I'm used to since having the Mirena. Prior to pregnancy and this type of birth control-I had very heavy periods, or no periods at all. I was extremely bloated lastnight. After intercourse with my Fiancé this morning, I was greeted with medium sz amount of bright red bleeding. I'm confused and scared! Should I be scared??