Westinghouse

Hello everyone, I would like to ask on here if anyone can give me some insight as to if you think I could have colon cancer. Around mid December of last year I didn't have much of an appetite and I was constipated. So I ate more vegetables/fiber. I ended up not being constipated after that, and my appetite sort of went back to normal. But then on January 21 of this year I woke up and felt fine, but then 10 minutes later I suddenly felt nauseous. I stayed in my bed, when the pain suddenly dropped down to my lower abdomen and I felt crampy. And ever since then I would have lower abdominal cramping, excessive gas, etc. I didn't notice any huge changes in my bowel habits. But I did notice that the pain was at it's worst below my belly button and about 1 inch to the right. It literally feels like something is in there. I have noticed that I have back pain directly behind where the pain is in my abdomen. I have also had some right leg pain as well. And I wasn't super concerned about this, but I noticed my weight has been changing. Now when this was occurring, I didn't have much of an appetite. I wasn't eating much and I was really depressed because I really thought (and still think) I have cancer. Therefore I thought I was losing weight because of that. I'm usually around 135, but I was around 132-133 for the longest time. Then suddenly 4 days ago I weight myself, and I was 130.2 pounds. It literally happened overnight. I have since been struggling to even get above 131 pounds. I went to my GP about this and she felt my abdomen and listened to my bowels and said everything sounded healthy. She diagnosed me with IBS. I wasn't too convinced with that diagnosis, and went to another doctor and he did the same thing, but he ran blood work to test my red blood cell count, white blood cell count, and everything in between. All results came back normal. Now I'm still concerned about this whole thing. It literally feels like there is something in my right abdomen, but my abdominal pain has since gone away mostly, but the weight loss is what is scaring me. Like I said, I told both doctors about it and neither of them seemed concerned. I haven't been tired at all or anything like that, and I'm not anemic based on my blood tests. I have noticed also that I have started feeling like I have a cold/cough thing going on lately. I will wake up in the morning and have thick chunky phlegm...sorry about the description. But as the day goes on it seems to get better. I also have noticed my anxiety seems to be worse again. So what should I do? Can I possibly request a colonoscopy from my doctor?
I'm 19 years old and a male.
I swear I wouldn't be posting on here if I wasn't really concerned.