Thanks for your question on Healthcare Magic. I can understand your concern. Yes, possibility of muscular spasm is more. But since it is left sided chest pain associated with left shoulder and arm, better to first rule out cardiac cause for this. So get done ecg and 2d echo. If both these are normal then no need to worry for cardiac causes. Muscular spasm is likely in your case. So avoid heavyweight lifting and strenuous exercise. Avoid bad postures in sleep. Avoid movements causing pain. Take muscle relaxant tablet. Apply warm water pad on affected areas. Gentle massage over involved region can also be helpful. Don t worry, you will be alright. Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.