What to do for ringing in the ears from concert?

Wait: Concert volumes are way too loud generally speaking. You can actually enjoy a concert with ear plugs or other hearing protection in place. You may have suffered from hearing trauma that caused damage manifest as ringing. A best practice for future concerts would be to adopt a preventive posture, and wear hearing protection.

Very common: You see, the loud music is measured in high decibel levels, and persistent intense noise causes immediate tinnitus, but repetitive occurrences can lead to permanent high frequency sensorineural hearing loss. Hate to "rain on your parade", but might consider using small insert in external ear for protection. Available in numerous sporting goods stores. Also, headphones can adjust for frequencies