I have had abdominal pain in my left lower abdomen
It could be many things
What you describe could be a hernia, although this can usually be seen on a CT scan, especially if you do a Valsalva maneuver at the same time, as this will push a hernia through the abdominal wall. Have you had abdominal surgery in the past? Did you have biopsies during your colonoscopy?
Any fever, vomiting?
Looking forward to hearing from you.
It sounds like IBS
I understand your concern, but given your young age, cancer is very unlikely.
In general, small bowel cancers are extremely rare. Your symptoms are suggestive of irritable bowel syndrome. I suggest you try a simple over the counter laxative, e.g. movicole.
Let me know if it helps.