Hi thanks for asking question. You can have following differential diagnosis. First one it might be simple musculoskeletal pain as no other specific symptoms are present.Take enough rest with proper sleep posture. If pain more simple analgesic can be taken. Secondly though chances are less heart problem has to be ruled out by doing simple Electrocardiogram(ECG). Third rare possibility is off respiratory problem if associated cough and fever is present.If suspicion of that x ray can be taken. You have no serious problem, on preliminary approach investigate with ECG and CRP estimation with simple analgesic. I hope my suggestion will help you.If still have problem then further work up is to be done according to physical examination and further history