I Get Bump On Public Hair With Pain

I am 23 and a Male. Sometime I get bump on my public hair and it does get pain only if something touch it. When bump pop up on pubic hair , in next few day, a little long strip bump start to grow on at end of public hair next to thigh. It s does hurt. I can t walk normal, I have to walk careful with pain. After few day, pain is better but bump still there. In meanwhile, it s slowly fade. However, it not the first time I get it. It s been on and off for like 3 years. I kept wondering why it keep coming back. I did went to doctor few months ago, they said there is no infection or anything. It just like a pimp but inside. How can I stop getting like that?