Gastritis is an inflammation of the stomach lining, causes stomach upset, irritation, and pain. Viral syndrome is an unidentified cause of typical virus symptoms sore throat, stuffy nose, aches and more. Excessive caffeine use can cause irritability, difficulty sleeping, anger, depression, and fatigue. If you suddenly stop drinking caffeine, you get withdrawal symptoms, such as headache, fatigue, and bad mood. Malocclusion is misalignment of the teeth such as underbites, overbites, and crossbites.