13 weeks large gush of blood. ER couldn’t find anything wrong

Destiny

Hello. I’m 13 weeks with my second baby. I had a c section with my first. Yesterday I was in pain around where my c section scar is. It was continuous all day but mild (I didn’t take any painkillers or anything). I was laying my daughter down for bed and she asked me to go get her toy off the couch. I did and on my way back to her room I felt a large gush of fluid. I ran to the bathroom and before I made it there I had blood literally coming out of my pants and dripping on the floor. I also had some painful cramping once that happened. I went to the ER and they couldn’t find anything wrong. Baby boy was looking fine and bouncing around in there. They ended up sending me home while I was still cramping and still bleeding. Today I’ve still been bleeding but it’s less and brown now instead of red. But I still feel like I was hit by a truck. My whole abdomen is sore and tender.

They told me it was a threatened miscarriage. I had a miscarriage prior to this pregnancy at 5 weeks.

Has this happened to anyone else? I’m obviously nervous it could be a warning sign of an impending miscarriage. Thanks!