Sharp pain in tooth few months after root canal treatment. what can i do to alleviate the pain?

See your dentist: Call your dentist. Pain a few months after a root canal is not normal. Over the counter pain meds may help or your dentist can prescribe something stronger. Or you may need an antibiotic. Your tooth may require further treatment despite your dentist's best efforts.

See dentist: It may be that you fractured/split your tooth. If you did not get it filled and/or crowned after the root canal, it might have been too weak to take the stresses of chewing. See your dentist asap, to check and treat.

Go back to the docto: You should not be experiencing discomfort months after a root canal. The nerve should have been removed during that procedure and should not be causing you pain for this long. Go back and be evaluated by the doctor so it does not lead to worse problems! he will know what's going on.