<s>[INST] I have a knot on my left side on my rib cage and it is very swollen and painful. It has been there since before Christmas and I have had multiple tests run and they all came out negative but the know is still there and super painful and swollen. I am female and 18. The past few days it has been worse than usual and my body has been having shaking episodes, like vibrations in my hands and feet and mouth and head. My doctors don t really want to help me. Any idea what it could be? [/INST] Thanks for your question on Chat Doctor. I can understand your concern. By your history and description, possibility of either osteomyelitis or herpes zoster infection is more. Herpes zoster is skin infection common in chest area. I cause painful lump. Osteomyelitis is bone infection common in ribs because ribs are flat bones. So better to get done clinical examination and ultrasound examination of local part for the diagnosis. You may need antibiotics and antiviral Chat Doctor.  Warm water pad application on lump is advised and will reduce your pain. Hope I have solved your query. Wish you good health. Thanks. </s>