29y/o male, had tiny thin stools for a few days followed by constipation happening right now, took miralax and saw greenish black little specks/chunks in my stool, im terrified right now, is this a sign of colon cancer? there was no blood or mucus?

Constipation: Colon cancer would be unusual in your age bracket. Blood in stool and change in bowel habits are 2 common symptoms of it. Greenish black specks are nonspecific. To treat constipation, increase both fluid and fiber intake(can also take fiber supplement like Metamucil) in your diet. Try to avoid laxatives. If not improved, consult a gastroenterologist for evaluation and advice.