I get mild cramps almost all the time, especially whenever I'm spotting...even if it's just brown discharge. I'm also having terrible constipation so that never helps but I have noticed that I feel crampy and slightly "off" just before, during, and shortly after a spotting episode. I lie flat and still as much as possible when that happens.
When I passed my clot my cramps were definitely severe. I would compare them to be almost equal to my miscarriage. Like I said, there was a reason I thought I had lost it. I was even getting condolences from the nurses at the hospital. Imagine my shock when they found a heart beat on the ultrasound!
But not everyone passes the clot or even bleeds. Often it gets reabsorbed. The vast majority of cases with sch end up with healthy, full-term babies. Yes, the risks are increased but not as much as some sites on Google would have you believe.
I know it's very scary though. I still live with that fear pretty much everyday. Especially as my last bleed was unexplained. I'd rather just know.