Why is my tooth falling apart?

I had a root canal done nearly two years ago on one of my upper tooth in like 3rd to last from the back due to tooth decay. Then I had a filling. After over a year and a half, the filling came out. And few months after, a piece of my tooth fell off. And somehow today, I felt just slightly minor pain in my tooth and my tongue touched the tooth then it started moving. Its the last part of my tooth left of that tooth that I had a root canal done. Do I let the tooth come off? I don't know if I can see a dentist soon because I don't think I have Medi-CAL or medicaid.