Withdrawal or breakthrough bleeding?

I've been on Trinessa for several months, and then I missed two days after my last pack (after the 7 inactive pills).  So I started taking the new pack two days late, and then three days into it, I was put on the antibiotic doxycycline.  That antibiotic made me sick so I was put on Augmentin.  In the past couple of days, the dose of Augmentin was increased. (I have been on antibiotics for 3 weeks now) I've been having heartburn and hot flashes for a few days (before the increased dose). Now I'm experiencing some light bleeding when I wipe, it started off barely visible and pink, but after intercourse it was a little heavier and brown (still only when I wipe.)  I have 4 more active pills before the inactive ones.  Am I experiencing withdrawal bleeding due to the antibiotic or could it be implantation bleeding?