ICD-10-CM > M00-M99 > M70-M79 > M79 > M79.1 M79.1 Myalgia Non-Billable/Non-Specific Applicable To Myofascial pain syndrome Type 1 Excludes fibromyalgia (M79.7)myositis (M60.-) Codes M79.10Myalgia, unspecified siteM79.11Myalgia of mastication muscleM79.12Myalgia of auxiliary muscles, head and neckM79.18Myalgia, other site