Firstly I have never had sex so I am sure that it can't be an STD and the fact that it first happened when I was about 10. I am 19 now but it very rarely happens and happened to me today, it is a very uncomfortable feeling and has sometimes become slightly painful, it happened this morning after I had urinated and had a shower, it lasted quite a while, maybe 20 or 30 minutes. It feels as if I have urine blocked and when I get a bit out I feel slightly better. I am just wondering if this is harmful because it has happened to me for quite a few years but only once or twice a year at the most. I have looked at various causes online ranging from acidic urine to STDs and urine infections. Is there anyone that could help me and would know what my problem is because I am slightly worried.