I Was On Impanon For 3 Years And Now Have

I was on impanon for 3 years and now have been on nexplanon for 2 years. So it has been 5 years since I have had a period until recently. I got it at the end of July and again end of August. But then last week I got it again and then stopped after a couple days. Now I am spotting again. Is this normal to now start getting a period so irregularly after not having one for over five years. Why am I now getting them again?