Narrow Stool, unexplained weight loss? Do I have colon Cance

I'm almost 16 years old and over the last 2 weeks Ive noticed my stool is narrower and Ive been losing alot of weight and I'm not active, maybe its because I'm worrying too much. Im trying to force my self that the only reason I have narrow stool is because I dont eat veggies and fruit as much anymore and I eat very bad food, maybe thats the cause? But that doesnt explain the weight loss, whenever I get a chance to eat ( Because I work at mcd's 5-8 hours at a time) I eat very badly. I've been getting dehydrated alot too, could that be linked? Plus my exzema has gotten alot worse, I just need an answer if I should tell my mom or not and if I should see a doctor... I'm very scared at the moment, anything will help

Well, you should certainly tell your mom that something's going on and you should have this checked. I suppose that this bad food would give you constipation and make you gain and not lose weight.

It doesn't necessarily mean it is cancer but underlying causes should be investigated and the sooner you do it, the better.