So Scared That I Have Colon Cancer....

Hello, I'm just sitting here really really worried that I have Colon Cancer (I have a dr appointment tomorrow). I've had some real tell tale signs of the disease, let me first say that i'm 23 years old and a white male. I've noticed lately a decrease in appetite, over the past few days i've also noticed i've been losing weight (down to 154, usually around 156-159), my stomach has been feeling weird, i had diaherra, and after the diaherra I had a thinning of my stool (it was thinner, now it's a bit more bulky), also feel like I haven't fully defecated. I haven't noticed any blood in or on my stool, I guess that's the only thing going for me at this point. I've been crying off and on for a few days now because i'm so scared. I guess i'd just like to know, if anyone with Colon Cancer could tell me some of their early symptoms? and any other input would be great.