I should get my cavity treated right away... but I'm 고민이네요.

I have been working for quite some time since I started living alone away from home.

A few days ago, I looked in the mirror and noticed that my teeth seemed a little darkened, so I went to the hospital.

When I went to the dentist, as I expected, I heard I have a cavity. I finally got my paycheck from work, but the treatment costs for filling are quite high. I'm planning to get treatment next month because this month is tight financially, but I'm wondering if it's okay to leave it untreated for about a month, and I'm worried that it might worsen significantly in the meantime.

Actually, if I want to get immediate treatment this month, I have no living expenses left, so I think it will be very difficult.. What should I do?