I’m freaking out

So, after almost every period is over, when i am ready to have sex again, I do it and then a day or two after I get this weird thick discharge that is sometimes mixed with blood. I know the blood is probably just old blood that didn’t come out, but, the thick/chunky 🤢 discharge scares me because i was looking online (I know, big mistake) and it kept saying that it is an std, but I have only ever slept with one person and it has only been happening recently, it never happened before with this person. I’m to scared to tell anyone cause it’s embarrassing, I’m getting a new doctor soon so I will be able to talk to her but right now I have a guy doctor and I don’t feel comfortable talking to him about it. Help me!