Hi arroncraig. Welcome to the forum.

I'm not a doctor, however I'm going break my own rule and diagnose you with the disease of HyperGoogleItis. Also known as too much Googling. 

To answer your specific question, there is a possible link between low B12 and digestive cancer, but that is only half the story.  The risk of digestive cancer at age 24 is very low, and so all the reduced B12 might do is increase that very low risk ever so slightly.  Resulting in a risk that is still very low. If I were in your situation and at your age, I would not be unduly concerned. 

Unfortunately, these are nuances that can be missed when consulting with that quack Dr Google, which is why most of here know when to lay off Google.  

So, the best you can do for now is stop Googling, try to keep calm and get on with your life as normal. The doctor may well refer you for more tests, and the colonoscopy might or might not show anything useful.  I'm afraid you just have to go with the flow for now. 

Thank you, you have some what put my mind at ease.  I’m laying off google for time being because it is adding to the stress. Haha

Thank you for taking the time to reply! :)

Thank you, you have some what put my mind at ease.  I’m laying off google for time being because it is adding to the stress. Haha

Thank you for taking the time to reply! :)