Spotting and discomfort

I’m 8 weeks pregnant with my second child. Wednesday I had my first ultrasound and everything looked great and we heard the baby’s heartbeat, but today I woke up with pink (some light some brighter) spotting and as the day as progressed it has stopped or is sometimes very very faint but I’m having pelvic discomfort almost resembling mild cramps. I called my doctor and she assured me it could possibly be 8 week (placenta I guess) implantation. But obviously I’m still freaking out a little. Before my first baby, I had a miscarriage and a year after my daughter was born I was newly diagnosed with PCOS- which I know can increase your risk of miscarriage. Any words of wisdom?