Re: colon cancer?... I'm very scared!
I completely agree with Mipsy. Your test results were good and the blood is almost certainly from your period.
I know you are scared but you've had a scan and nothing sinister came up. A little bit of pain in your digestive system is, I would say, a completely normal occurrence for most of us from time to time. It could be gas. Hopefully the GI doc will put your mind at rest.
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Under no circumstances will I consult Dr Google for any medical advice whatsoever.