I am 15 years of age, With A lower back pain, Can anyone help?

i am 15 years of age, I have a lower back issue that hurts tromedisly when;Coughing, Sneezing, Standing up straight, Sitting, Sittin and moving my head down, bending down, lifting anything, standing for a period of time, activities involving running, Throwing and kicking. its been like this for about 2 months and the pain has deffinitly been getting worse day by day. i dont want to make a big deal out of it if its not anything serious but it does hurt alot. I also had a horrible amount of pressure and pain on the left side of my stomach and abdomin, i couldnt walk with that pain or stand up straight, i also felt better laying on my back, I have tryed Icing, heating, advil/Ibreprophen, Laying down for a long while of time and nothing seems to be getting better. any idea's?