Symptoms after new sex partner

Patient: In March I got a new sex partner. We ALWAYS use a condom. After the first time we had sex my outer left leg started to hurt down to my foot. I went and got tested for every std a week after and tested negative. I retested a month later and then again 3 months later. All results are still negative. I even took the HIV 1 RNA test a week ago and that was also negative. I still have a slight pain in my left leg, the left side of my groin feels tight and my left armpit feels sore. What could it be?