Injectable contraceptive and injection time ...

I took the injectable contraceptive today, it's the 3rd month, all on the same day 20. But today there was a normal reflux, not to mention that the girl who applied massaged the place, and I already knew that I could not, painful, but had this reflux of the medicine, a good amount. Should I worry, too much or too little?
Expert answer:

In doubt use condoms during this month.