Hello ma'am and welcome.
You are not menstruating, this is most probably residual blood as your doctor suspected or a possible bleed. This could also be a completely normal process, but it is better to get it looked at.
I would recommend a bimanual examination, speculum examination and an ultrasound
investigation to be conducted just to make sure all is well. But may be in a few days time. Let us wait to see if things normalize.
Hope this helps.