Lying down hurts my back :(

Hi, I'm a 16 year old male and I seem to be having some issues with my back. I am not 100% sure if it's my muscles, my spine or a mix of the two...but when I lay down (and the pain is there for a few seconds, maybe 15 at most) I get a loss of breath and it feels like my back is stretching out or trying to cope with the surface. It isn't so much pain as it is a very uncomfortable sensation in my back. I want to say it ranges from my upper back down near my lower back. I can't remember how long this has been going on, but I know it was recent from the past few months. I haven't injured it or done anything that would in that time period and I am curious as to WHY this happens and how I can remedy the situation.

Thank-you in advance.