If the majority of the GI tests are negative, you may want to consider irritable bowel syndrome. Typically, this can cause crampy abdominal pain with alternating diarrhea and constipation such as you describe.
You mentioned that you had a negative colonoscopy. Possible treatment options for IBS to reduce the spasms would be medications such as dicyclomine and hyoscyamine. Their selective inhibition of gastrointestinal smooth muscle reduces stimulated colonic motor activity and may be beneficial in patients with postprandial abdominal pain, gas, bloating, and fecal urgency.
There is also the possibility that the left sided hip pain may not be GI related. You may want to consider more extensive imaging (i.e. an MRI) to see if any abnormalities of the joint are contributing to your symptoms.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Thanks,
Kevin, M.D.