Breastfeeding & Potentially Pregnant

Mica🌻

I'm 4.5 months postpartum and breastfeeding and I know many don't experience a cycle. But I have every month for a few days. Recently, I had a slip up on the 7th, what I thought was a cycle on on the 15th. But it's was an extremely small amount and nothing more, didn't even last a day. It's been some days and I feel mild cramping in my lower stomach and back. Scared it's implantation bleeding. Is it too soon to take a test?