A hard lump inside the diaphragm fossa with a little pain can usually be treated with medication under the guidance of a doctor. A hard lump inside the diaphragm fossa with a little pain may be caused by enlarged lymph nodes, boils, sebaceous cysts and other reasons. 1. Enlarged lymph nodes: generally refers to the lymph nodes are infected or breast hyperplasia caused by the lymph nodes increase in size, may be due to external factors, infectious diseases and other reasons for the cause, the patient can be under the guidance of the doctor to use amoxicillin, quinolones and other drugs for treatment, to any kind of quinolone allergy to prohibit the use of this drug. 2. Boils: Boils are generally acute purulent infections caused by bacterial infection of individual hair follicles or sebaceous glands of the skin, usually caused by malnutrition, unclean skin, etc. Patients should be treated with fusidic acid cream, mupirocin ointment and other medications under the guidance of a doctor, and the drug is contraindicated for those who are allergic to any of these ingredients. 3. Sebaceous cysts: Sebaceous cysts are usually retention cysts formed when the sebaceous glands’ excretory ducts are blocked, which may be caused by dust clogging and bacterial infections, etc. Patients can be treated with Plurilifloxacin tablets and Chlortetracycline ointment under the guidance of a doctor and are not allowed to use the drug for those who are allergic to other tetracycline antibiotics. Patients should go to the hospital in time to find out the cause of the disease under the guidance of the doctor and carry out treatment. The above drugs need to be used in a standardized manner under the guidance of a doctor.