Thanks for providing more information.
As you describe,most likely possible cause may include Coccydynia(inflammation around tail bone).
Main line of treatment may include NSAIDS(Motrin),use of a therapeutic sitting cushion to take the pressure off of the tailbone when sitting.
Steroid injections can be advised in case of chronic cases.
You should also take metamucil and fibre rich diet.
As you have repetitive history of injury at same position so it's good to undergo a clinical examination by an Orthopedist to rule out associated malignment which can cause crunching sensation.
Do gentle massage with muscle relaxant ointment and apply warm compresses with a heating pad on affected area.
Also physical therapy can be helpful.
I hope this helps.
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