What's wrong with my teeth!?

I'm 15 years old I am a girl, I brush every morning and night I don't floss daily though because it make my teeth feel loose but thats not my problem....my front teeth hurts and it is loose slightly my gums are kinda white before i brush them in the morning and before at night. My bite is not proper anymore and it doesn't fit right and when i bite down lightly my bottom teeth feel tight. Before I had a check up 6 months ago they said my teeth were perfect just had to brush the front teeth more no cavities. But they also found something in the x ray or something this black spot they couldn't detect what is was all they said is they will do surgery in 5 years or whenever it starts to hurt. I have a feeling they had no clue what it was. now I feel like my teeth are dead what can I do please help I made a appointment it is this Thursday four days away and I'm freaking out i even have a exam tommorow i can't even study now please help has anyone gone through this before? I'm not wiggling it and I'm drinking milk but I guess it won't help in my case they aren't full out loose. I also hear a clicking sound with the loose tooth will I end up loosing my teeth help is it a disease infection! I'm in Canada so I don't need to worry about the check up costs cause it is free so I will do anything help!