Inflammation of the cavernous or spongious tissue as well as inflammation in other parts of the body is accompanied with pain, swelling and red inflamed area. If none of these is present, inflammation is very unlikely. It is very hard to give the right diagnosis without a visual examination preferably done by a urologist. Depending on the cause, it can be treated with: antibiotics in case of bacterial infection, or topic corticosteroids if inflammation without infection has occurred. The exact medicine, if any needed, should be prescribed by a urologist. If you feel embarrassed and there is no sign of inflammation, as well as further thickening of the shaft then you might want to wait for 1-2 weeks before visiting a doctor. Many boys in puberty pay more attention to their penis and any change due to puberty can trigger the alarm unnecessarily.