Abdominal pain - first period after miscarriage

I miscarried back in March and got my first period this week. Middle of day two I had extreme booting and abdominal pain which I blamed on constipation... but it’s been three days and the pain is sharp that have now moved to the bottom of my tummy around the belly button, every time I eat it’s horrible pain. Period Cramps are sharp and stabbing... period isn’t too heavy for the first one but it’s not normal either... has anyone else been through this?

I went to the doctor and they want me to have a abdominal ultra sound... hoping that this goes away soon. Could it be from the tampon?