14 hours duration and constant pain without any other suggestive signs or symptoms is more likely to be muscular. You should give more details about its nature, relation with breathing, movements, presence or absence of cough, sweating etc. What is the record of blood pressure and blood
sugar should also be posted. Seems myalgia. Take rest. If anything appears new like breathing distress, severity ofpain increases then don't take chances, get an ECG done by showing yourself to a qualified physician.