Overuse vs injury
Tendinitis is likely if you have an overuse or cumulative trauma type injury.
Localized pain directly over the tendinous origins of your forearm muscles that worsens with resisted activity is a hallmark of tendinitis. The outer prominence (lateral epicondyle) is a common site for tendinitis and is painful with resisted wrist extension. Stepwise treatments: rest, ice, nsaids
, brace, and injection.