Workout gave me cramps?

I'm trying to get back into working out to make myself healthier (my husband and I are TTC) and did this workout tonight. I could only get through one round though because I started getting these pelvic cramps (like I do on my period). Never had this happen before. My lower back was aching a little too and I've got a chiropractor appt tomorrow. I'm wondering if the back pain is maybe what caused the feeling of cramps or if I pushed myself too hard. Has anyone had this happen?