11 weeks pregnant and spotting blood

So last night when I wiped there was blood on the tissue, like red fresh blood. I must of wipes like 3-4 times and there was streaks of blood in every wipe. I wasn’t in discomfort and didn’t experience any type of cramping. I have never experienced this in my first pregnancy so this was alarming. I went the ER and they did an ultrasound and said baby is fine and that the bleeding was coming from my uterus but that it was normal. The next day everything was back to normal, no spotting at all. Has anyone experienced light bleeding during pregnancy? Couldn’t it be that I strained myself without realizing?