I've had stomach cramps for two days. Diarrhea yesterday and constipated today. Haven't taken anything for it. Never had this problem before, always r?

Constipation. If you had multiple bowel movements it is not unusual to skip a couple of days of movements. Your regularity will eventually return as you continue to eat a normal diet. The diarrhea may have been from something you ate or from a mild viral intestinal infection.
See your Physician. Abdominal pain, diarrhea and constipation has many causes. Appendicitis, any foreign travel, bacterial, viral or fungal infections. Or could be from eating new or unusual foods. If accompanied by fever; need to see Physician as soon as possible.