Hello, Pain and tightness under the arms is commonly due to enlarged lymph nodes, muscle strain, angina pectoris, etc. Tightness radiating to the right side of the thigh is indicative of dehydration, stress, or underlying health condition like infectious mononucleosis, Lyme disease, fibromyalgia, polymyalgia, rheumatica, etc. that needs to be urgently looked upon. Your husband is advised to get clinically examined by a GP, get all required blood tests, imaging tests and investigations done. His treatment will depend on the pathology detected and the severity of the symptoms. Get him treated at the earliest. In the meantime, he can take a gentle massage on the area affected with a pain relieving ointment. A warm bath is said to help relieve such symptoms. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician