It causes tender, reddish lumps usually on your shins, which can look like bruises. It may start with flu-like symptoms such as fever and aching. It’s the most common skin problem linked to inflammatory bowel disease (IBD) and is related to your immune system’s response to bowel bacteria. The bumps tend to show up when your IBD flares and go away when you treat it. To ease the pain, keep your legs elevated and apply a cool compress. Pain relievers, like ibuprofen or naproxen, may help, too.