Please help with my question:( :(...?

Hey, well basically my teeth have suddenly gone really horrible. About three are decaying, and my gums are bleeding and tender. ive suddenly got loads of gaps where food gets stuck and then makes my gums bleed. I'm really upset about it, and scared about going to the dentist, let alone the huge bomb its going to cost! My sisters have got lovely teeth, and mine have just gone to pot really (abnormally) quickly:-( ive got a dentist appointment in a month,can my teeth be saved? i'm only 20, its really getting me down, they are all I can look at atm.. I dont want to loose my teeth :-( xx