Bleeding on the pill - I've seen a doctor and had testing

Has anyone gone back on the pill after having a baby and had bleeding when your not meant to? (In between periods) i am at a loss as to why i have lost around 20kg since having my daughter and now i am having breakthrough bleeding also bleeding during intercourse... (papsmear came back with the all clear)

http://www.theimperfectmum.com.au/quest…/16547/bleeding-pill