Yellow discharge? 3 months Pp

Jane

So I had a vaginal delivery. Never had much discharge r anything over past months. Then started to have sex n my husband pulls out. Idk

If it’s a coincidence but now I’m having yellow discharge n thick. It’s been a few weeks since we had sex but I notice it almost shortly after. Like days later. No he didn’t cum inside me. What could it be? I also ebf my son. Is it a yeast infection? Goes away for few days but seems to happen after sex