I think I'm clincally depressed. Am I?

For a a while now I've lost interest in alot of thing I used to love. My friends have noticed a huge difference in the way I act. I hafta force myself at thing I would usally laugh at. I feel like I have the giant sob in my chest an I can't get it out. I'm running out of energy too&lately all I wanna do is run extremely fast on the treadmill so I forget about life. I feel like I hafta force anything happy. I'm going to the thearpist soon. Is this a good decison? (I am 13 by the way.) my mom thinks maybe the thearpist could put me on a medication to help. Has anyone Been throughthis before? How can I stay happy till my appointment? I am too young for this? Help will be much appreciated.