Painful breasts, grew quickly, very uncomfortable!

I'm 16 years old and i have 10DD bra size, and my breasts were always normal until a few moths ago when they suddenly just became very saggy almost instantly, they grow very quickly and have lots of stretch marks and they are overly saggy and it is painful, i've tried alot of things found on the internet to prevent but i think my only choice is surgery because they are extremely painful, and extremely uncomofrtable and it hurts to take my bra off, they are very very saggy and it is horrible, not because it is unattractive but so uncomfortable, this shouldn't be normal for my age, none of my friends have a problem like this and some have e cups. what is wrong and what should i do?