Swelling is the potential cause for pain more so pain on pressure when you apply on the inflammed part. The question here is why this swelling. This can be due to some infection or injury
or muscular tear. Anti inflammatory and analgesics work good but if associated with infection anti biotics may be needed. Amongst herbal medicines we use punarnava guggul trifla guggul and milk with turmeric in it. locally apply myostaal gel.