Y is my back killin' me?

This weekend was incredibly crazy because everyone campus was partying hard. I normally do not join in with the festivities but I decided "y not?" I had a great time, but when I woke up Sunday morning my back ached horribly. I could not pin point what could have caused this pain. I don't remember falling or being involved in anything painful lol. I pondered on the reason all yesterday but could not figure it out. Finally, this morning after I woke up I set up straight to stretched and my back cracked several times(a lot more than normal). It instantly felt better and that's when it hit me. I'm a huge sloucher and I'm not proud of it. I never really pay attention to it until I see a picture that I have taken and I look horrible. Well, over the last couple of months I am getting more and more chest heavy. Since, I have a pretty small frame this may be a good look for me, but it has made my slouching even worse. I never noticed how much it has been weighing me down lately. So I'm going to try to working on my posture and hopefully this will help.