Can a high spot on a crown cause sensitivity in a tooth already treated with root canal therapy?

Unfortunately discovering the problem with that area requires a proper examination with x-rays, probing etc. In this forum, you haven't provided enough info to diagnose a specific problem. An evaluation by your dentist can rule out several possible scenarios and get to the root of your problem. Rarely will antibiotics alone solve any dental problem permanently.

Without additional diagnostic information it is impossible to give you a specific answer. There may be several causes for your problem. It would be best for you to get an appointment with your dentist for a correct diagnosis. 

Hello,
Sometimes when a tooth is treated with endodontics the patient may have sensitivity due to tissue inflammation of the periodontal ligament. Another reason is for the placement of rump insulation. It is advisable to go with your dentist to discuss any doubt.