Spotting

I’ve been on the mini pill (desogestrel) since September. I’ve no periods and I’m breastfeeding my 1 year old. When I woke this morning and went to the loo I was like “spotting” when I wiped. I’ve had loads of cramps and dull achy pains but no blood since.

I’ve no had intercourse in a few months so not pregnant. Is this normal? I know the mini pill is meant to stop periods