There are a couple of possibilities. The cement that was used maybe causing the sensitivity, the
nerveNerve biopsy
Nerve conduction velocity maybe inflammed from the
preparationPreparation h hydrocortisone of the teeth, or the crowns do not fit. Root canal therapy is a viable treatment but I can not tell you if that is necessary or not. I think the amount of discomfort you are experiencing is a determing factor and whether or not you want to seek out another opinion which you certainly have the right to do.