Severe Cramping

I have my tubes tied for about a year now and my period was two days late this month and came on earlier today... I had severe cramping to the point where I couldn’t walk or move and I was considering taking a trip to the ER. It was so painful to the point it made me nauseous but the bleeding was very light I was and still am pretty much spotting. And the severe cramps lasted for a couple hours and now the bleeding has almost completely stopped... any clue on what happened