had a baby 10 wks ago had first period since which was ok now im having abdominal pain with bleeding between periods ??

this is the second period ive had since i had my baby i had bleeding between them ive had abdominal pain and bleeding after sex once im breast and bottle feeding. this period has been different day one was normal second day had almost stopped and was dark brown and clotted third day its light pink with lots of mucus any advice would be appreciated.