Lots of women experience cramping and their period or ovulation aren't always to blame. Unpleasant sensations in your pelvis throughout the month may have other underlying health conditions.

Digestive tract issues: diarrhea, constipation, food allergy, poisoning, spasms, IBS, etc.  

Reproductive organ issues: pregnancy, cysts, endometriosis, and so many more possible causes.

There’s usually no reason to panic, as more serious conditions are often accompanied by additional symptoms.

Inflammatory Bowel Disease  

The cramping sensations may vary: cramps and pain in the right lower or middle parts of your belly that are mild to severe (Crohn's disease) or cramps on the lower left side of your stomach (ulcerative colitis).

This means you get chronic irritation and swelling in different parts of your digestive tract. It happens when something goes awry in your immune system.  

Other symptoms:

• Fatigue

• Fever

• Sudden and severe constipation or diarrhea

• Urgent need to poop & feeling that your bowels aren’t completely empty afterward

• Blood in your poop

• Weight loss

Irritable Bowel Syndrome

This disorder causes stomach pain and bloating with diarrhea, constipation, or both.

What the cramps feel like: They're sudden and in your belly. They might go away after you poop. Your specific pain will depend on whether you have constipation or diarrhea. You might go back and forth between the two or only have one type. Symptoms usually get worse during your period.

Other symptoms: Pressure, stomach sickness, gases, mucus in the poop.  

Pelvic Inflammatory Disease (PID)

PID is a bacterial infection that's usually spread by sex. It affects the parts that help you conceive and grow a baby.  

What the cramps feel like: You'll have pain on both sides of your lower belly and lower back any time of the month.

Other symptoms: abnormal vaginal discharge and, sometimes, spotting. It can also cause pain or burning during sex or urinating. Changes in periods - they might become heavier or longer.

You'll need to get the disease treated by a doctor.

Pregnancy pain

You may experience a few slight cramps during the first 4 weeks of pregnancy occuring around the time when you’d get your period. If you aren't sure whether you're pregnant, take a test. Mild cramps followed by sharp, stabbing pain on one side of your lower belly can signal an ectopic pregnancy, which is a dangerous condition. If your test is positive and you have sudden pain that you also feel it in your shoulder and lower back, contact your ob-gyn immediately.

Endometriosis

Endometriosis-related cramps seem like regular period cramps, but they can happen at any time of the month. You may also have cramps and pain in your lower back and stomach below your belly button.

Other symptoms: Deep penetration sex may be painful. Some women may have painful bowel movements.  

It is a long-term condition in which tissue similar to your womb's lining grows outside your uterus.  

Ruptured cyst

The cramping sensations are sudden and sharp and may occur on either side of your lower stomach below the belly button. The location depends on which ovary had the cyst.

Or there can be none at all.

Cysts may sometimes form on your ovaries, most of them are harmless, but some can grow large and burst.  

Other symptoms: Some spotting, pressure or pain in your lower belly, thighs, or lower back and before the cyst ruptures, you may feel pain.

Cramps or pain in your pelvis may also have more underlying causes. If accompanied by sharp, sudden pain, fatigue, and fever, call your doctor ASAP.

Sources:

Why Do I Have Cramps but No Period? webmd.com