Diverticulitis: The patient's history of diverticulitis and the description of the cramping as similar to past episodes make this a highly plausible diagnosis. The symptoms of lower abdominal cramping, especially if they are intermittent and started in the morning, align with the typical presentation of diverticulitis.

Irritable Bowel Syndrome (IBS): Although the patient denies diarrhea, IBS can present with abdominal cramping, and the absence of other symptoms like fever or vomiting does not rule it out entirely.
Constipation: Intermittent lower abdominal cramping can be associated with constipation, especially if the patient has not had a bowel movement recently.
Gastroenteritis: Despite the denial of diarrhea and vomiting, gastroenteritis could still be considered, especially if the patient has been exposed to someone with similar symptoms or has recently traveled.

Appendicitis: Although the patient denies back pain and the cramping is described as lower abdominal, appendicitis can present atypically, especially in older adults or when the appendix is in a retrocecal position. Missing this diagnosis could lead to severe consequences, including perforation.
Ectopic Pregnancy: In women of childbearing age, ectopic pregnancy is a critical diagnosis not to miss, as it can present with lower abdominal pain and cramping. However, the patient's gender is not specified, and other symptoms like vaginal bleeding are not mentioned.
Ovarian Torsion: Another critical diagnosis in females, ovarian torsion can cause severe, intermittent lower abdominal pain. Like ectopic pregnancy, it requires prompt diagnosis and treatment to preserve the ovary.
Intestinal Obstruction: This condition can cause severe abdominal cramping, vomiting, and constipation. Although the patient denies vomiting, the presence of severe cramping warrants consideration of this diagnosis.

Inflammatory Bowel Disease (IBD) Flare: Conditions like Crohn's disease or ulcerative colitis can cause lower abdominal cramping, among other symptoms. However, without a history of IBD or additional symptoms like weight loss, diarrhea, or blood in stool, this is less likely.
Endometriosis: In women, endometriosis can cause cyclic lower abdominal pain, but it's typically associated with menstrual cycles and other symptoms like dysmenorrhea.
Lead Poisoning: Can cause abdominal cramping, but it's rare and usually associated with other symptoms like constipation, fatigue, and developmental delays in children.

Labs: Complete Blood Count (CBC) to check for signs of infection or inflammation, basic metabolic panel to assess for electrolyte imbalances, and liver function tests if there's suspicion of liver involvement.
Imaging: Computed Tomography (CT) scan of the abdomen and pelvis with contrast to evaluate for diverticulitis, appendicitis, or other causes of abdominal pain. Ultrasound might be considered for evaluating ovarian pathology or pregnancy in females.
Treatment: Depends on the diagnosis. For diverticulitis, treatment typically involves antibiotics and bowel rest. For other conditions, treatment will be tailored to the specific diagnosis, such as surgery for appendicitis or ovarian torsion, and supportive care for gastroenteritis or constipation.