Could it possibly be another cavity?

[Lovenest]

My son who is 5 just got a cap on his molar on the right in Nov and had his cleaning/check up then as well. We floss, brush and he chews xlitol gum 5-6 times a day. Here we are in Feb and on the left side by his first molar his gum looks like its missing a chunk or darkened.. It does not look like its on his tooth.. Its very odd. Could this be his tooth decaying that fast? Or possibly he some how cut it on food? He says its sore when I brush/floss it.

He would just flip out if I said we have to go see the dentist again. He has sensory issues and possibly aspergers. He does NOT like the dentist. We just spent a good chunk of money on his white cap, PLUS he had to go 4 times before the visit for anxiety reduction program.

Any ideas as to what this sounds like? Do teeth decay THAT fast?

[rose angel]

Unfortunately, I think it is possible My son had a similar thing happen. I think it was that he had a tiny cavity between the teeth, and by the time it broke through the top, it looked really big, really fast. He had a clean check-up in November, this happened in Jan.
Is the tooth sensitive to hot or cold food? I think that is a big indicator of damage that needs to be looked at.
ETA: my son's was on his tooth, not gum. So I don't know if my reply helped at all. Maybe have him swish some slightly salted water a few times a day? That would help a cut heal up..If it is a cut from food, etc, I think it should heal up quite quickly. Good luck!