Did you by chance have sex? That can cause pink. But if there's nothing more today I wouldn't be worried!
I too had a horrible cold with a Nasty cough, to the point I pulled muscles in my lower abdomen. Im 37 weeks but was 34 when i got sick. I'm not sure if it would actually cause you to bleed tbough, spotting is sometimes normal. I would just keep an eye on it and if you bleed again go in.