May have a sexually transmitted diseases

Guys I am freaking out! I’ve recently started talking to a new guy and out of no where I started feeling horrible. I don’t know if you guys know about canker sores but I have one of those now I have 5 little bumps on my lips! I am freaking out. Could I just be freaking myself out? I’m going to the doctor today but I’m soooo afraid of what they might say.