Strange discharge while breastfeeding

So it’s been about 2 weeks since I guest noticed this yellowish sticky discharge coming out (sorry for the tmi) picture in comments , and I’m exclusively breastfeeding and haven’t gotten my period back yet. (4 months postpartum) I’m not sure what’s going on but I doubt it’s a std as my husband and rarely have sex but I’m more worried it’s possibly a pregnancy?! Had this happened to anyone? Thinking about calling my Dr to ease my mind tomorrow. Tia!