Implantation bleeding or body off track?

i stopped using my birth control in august, got my period in september then around the time my period was due in october it was only for one day and was very light. i dont know if this was implantation bleeding or my body just not back to normal (although everything was normal in september). I have been feeling a little sick to my stomach this past week and sensitive to certain food smells but nothing extreme. Do you think i could be pregnant so soon after stoppin my birth control or body just not back to normal. my period was always normal before and while on b.c 28 day cycle

p.s was on ortho evra patch