There are two types of tendon pain. Usually it's an inflamed tendon sheath, which yields easily to NSAIDs. If taking NSAIDs don't help, then it's a tendon strain, usually at the attachment point. The only way to fix that is exercise, particularly heavy-ish low-rep work, just short of pain. Takes time. Tendons heal when they are stressed, not so much when they are rested, which is pretty much opposite what you do with an inflamed sheath. NSAIDs are diagnostic. I've had tendon strains which took 6 months to heal.
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