Symptoms to a miscarriage.?

Yesterday i had brown spotting when i went to the bathroom. Today i woke up and noticed it was a little darker and more red. I don't need any pantyliner yet its not that heavey. I have mild pain on my right side. I had an ultra sound done on tuesday and was perfectly fine before that. Had test results that said everything was great and the ultra sound stated that the baby was growin just fine. Could the ultra sound have triggered an miscarriage. B/c everything was fine before it then all sudden i'm bleeding 2 days after.