Oral and sore throat

So I had oral sex with the father of my child 2 days ago. We are not together. I feel disgusted with myself. He is pretty well endowed and it has been some months. 2 days later and I woke up with fever and my throat is sore. I did get really bad sinuses because of my allergies. I am currently breast feeding and freaking out because I hope he didn’t give me an std. Would it show up this quick?