The term 'Pain Inside' can be solved by the crossword solution 'ULCER', which is a five-letter word. An ULCER is an open sore or lesion that develops on the skin or mucous membrane, usually as a result of infection or inflammation. Ulcers can be caused by a variety of factors, including bacteria, viruses, and certain medications. They can also be caused by stress, poor nutrition, or other medical conditions. Ulcers can cause pain, itching, and burning sensations, and can be difficult to treat.