Temporary filling after root canal
I had a root canal about 6 weeks ago (on October 3), and I have a temporary filling since I haven't gotten a crown yet. I am attending college out of state, and I'm on my parents' insurance. I went to my regular dentist a few days before I left to go back to school, and he told me I needed a root canal, and sent whatever documents to the endodontist (near where I go to school) so that the root canal would be covered on the insurance.
I don't completely understand how my parents' insurance works, but when I inquired at the denal group where I got the root canal about getting a crown, they said that my insurance wouldn't cover it unless I change them to my primary provider. I don't think they were saying that out of greed or anything, because they actually advised me just to go to my current primary provider.
When I got the root canal, the endodontist said the temporary filling would be fine for about 6 weeks, and I need to get a crown. I told him that I won't be able to see my regular dentist again until mid-December, and he said it would be ok to wait that long. The temporary filling has been ok, but recently, it seems like it's been decaying. Should I be concerned about this? Can I do anything about it? Is it going to be a problem if I wait another month before getting a crown? Should I call the endodontist's office and ask? I am worried that the work done with the root canal will be damaged and I'll end up having to get the tooth extracted, which would really suck.