20 weeks with a single drop of blood

Yesterday we went on a road trip to Denver to see a NFL game so obviously I walked around a lot and sat in shaking seats from all the stomping from fans and I went to the bathroom at 3pm (it’s now 8pm the next day) after I wiped from peeing I wiped once more and there was a literal drop of blood. I’ve had nothing since and nothing before and no sex with my husband as well. I called my doctor on the road this morning and he thinks I could have just irritated my cervix yesterday but to keep an eye on it. Any one else with any similar experiences? Or any advice I’ll get in for a scan as soon as we get back and with how little it was I’m sure everything is ok but I’m also freaking out.