The pain in the right armpit is commonly caused by the following reasons: first, swollen lymph nodes caused by pain, when the body is infected by bacteria or viruses, it will lead to swollen lymph nodes, which will cause pain, which can generally be relieved by regular anti-inflammatory treatment, antiviral treatment, if necessary, you can also give drugs to clear heat and fire to relieve pain. Second, intercostal neuritis, which is often caused by local trauma, viral infection, can be localized by applying heat, but also appropriate to take more vitamin-rich food, such as apples, bananas, duck pears, etc., but also oral mild analgesic drugs, such as pain relief tablets. Thirdly, costochondritis, which is often a complication of upper respiratory tract infection, can generally be treated with physical therapy or oral mild analgesic drugs such as ibuprofen extended-release capsules to relieve pain. Fourth, there are also some rare causes, such as rib fractures. In short, if the pain persists, you need to go to the hospital promptly for consultation and treatment.