Tooth (molar) directly below recently placed cap now needs root canal - coincidence or result of incorrect bite?

Cap placed on upper molar 13 weeks ago & immediately had pain in the tooth directly below it. Bite adjusted a number of times - made the pain decrease significantly but not entirely. Last week, went back to dentist & bite was adjusted again but was told I now need a root canal in that lower tooth. However, pain has now significantly lessened and I'm wondering two things. 1- could bite being off have caused the damage resulting in root canal & 2- is it possible I won't need the root canal now?

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