Are you on any meds which might lead to a false-positive calprotectin result, e.g. NSAIDs or PPIs? Otherwise I do find it odd that you have a high calprotectin result but a clean colonoscopy. Was the barium MRI of your small bowel?
Meanwhile, constipation can cause abdominal pain and nausea. I know you say you're going now, but it's possible to pass lots of little bits and still be constipated. Is there any possibility you could be backed up with stool?
Also, have sources of pain outside the colon been considered? Ovarian cyst, kidney stones, etc.?
Dx Crohn's in summer of 2000. (Yay )
Tried and failed: 5-ASAs, azathioprine, 6MP, Remicade, methotrexate, Humira, various diets.
Had surgery Feb '13 - subtotal colectomy with end ileostomy. First thing to put me into remission in 13 years.
Had second surgery 10th July '15 to reverse the stoma and connect the ileum to the rectum. Officially flaring again. The fun never begins.