JSU

I have been exercise swimming for about 6 months now, 2-3 times per/wk. Each workout is moderate and lasts about 30 minutes. But recently the inner portion of my elbow has been bothering me. It feels like a bruise, but is on the bone and/or cartilage area. I thought it could be due to bad form or not stretching. I don't know for sure. Has anybody ever experienced this sort of thing before? It resembles "Tennis Elbow", but I don't know how I got this condition from swimming and how I can remedy. Thanks. JSU