Still have white bump

I had a white bump on my upper gumline. I went to my denist and he said that the tooth was dead. I had no pain with it. The bump looked like a white head pimple.

I had my root canle and a crown put on and my insurance well only cover  up to a thousand. So I am over my cap.

I looked at my gumline and that white pimple is back. It gets so big and pops and comes back. I do not get a bad taste and nothing hurts my gum is not red or swollen.

I go back in at the end of May for first six month check up whitch will be on me. I can not afford to go back in before than.

Any ideas ??????