It is common to experience irregular periods for a few months after going off the
pill.
You will treat this as a regular period – waiting the
minimum days from when you became
niddah before performing the
hefsek taharah, counting
seven clean days and
immersing.
You will calculate your
onot as usual from this period as well.
Please feel free to get back to us with any further questions.
B'Hatzlacha!