The possibility of mumps is very high. Mumps is caused by a viral infection, which manifests as a lump under the ear and pain, accompanied by difficulty in opening the mouth, because the swelling affects the temporomandibular joint, which causes pain at the joint. Treatment requires intravenous drip antiviral drugs or oral antiviral drugs. The treatment cycle is about 7-10 days, the swelling will subside, the pain can be reduced, and the patient can resume normal chewing function. At the same time, it is necessary to take more rest and drink more hot water during the treatment process to strengthen the body immunity.