Hi I Started The Depo Shot After I Had My

Hi i started the depo shot after I had my son in 2013. My periods stopped except occasional spotting. I missed an injection last December due to insurance issues. I started my injections again May 27th. I started having irregular bleeding but it only last a week or so before it was gone. After my last injection on August 29th I've been bleeding off and on for weeks. I bleed just about everytime I have sex. I just started back taking my iron pills for my anemia. What can I do to help stop the bleeding.