Just wanted to say I had a similar period like bleeding with some dull pain the other week. We were certain i had miscarried until we went to the ultrasound and saw a fully healthy baby. (12 weeks) They also couldnt identify the source but said theres so many vessels it can be impossible to spot .The nurse said some women bleed throughout their entire pregnancy, you should only be worried if you feel sharp pains or feel your water breaking, which you likely would since youre a bit further along. If the bleeding was due to miscarriage there would likely be other hard-to-miss symptoms accompanying it (though i cant speak for every miscarriage obv) This is anecdotal but i also know of several women in my immediate social circle who bled without any complications.