Root canal therapy. Canal crown occurs?

I completed my rct with crown towards July end 2021. At present i feel a slight pain on my crown only when i tap on my it. I have a very small pimple which is half the shape of an ant on the back gum of the crown and pains at level 1 on a scale of 1-10 where 1 indicates low pain. I visited the doctor, according to whom i had the pain because gums are causing the pain due to small food particles stuck between the crown and its neighbouring tooth. An xray was done, seemed fine too. A thread floss was used, i felt a bit relieved. The pain is not severe but it is there on a tap. Only sometimes when i bite it just feels off. Crown seems slightly thick too towards the front. I do not have sensitivity to air,heat or cold. I want to know is it possible to feel pain on a crown after months when an rct has been done on a crown? When do actually these pain on a root canal crown occurs? Ideally the tooth is dead it should not react.