Okay so I had my son 2 months ago. And I start back up on birth control last month. I went most of the month fine but i just started bleeding brown and pink blood lightly?? Me and my fiancé have had sex since I started it but he pulled out. And id been on birth control before I got pregnant and I never bled like this so I'm confused?? I've cramped lightly as well and I'm nauseous at night every night. & im on the pill to where I don't have periods!

Is this just breakaway blood? But if so why is it pink too?