A 27-year-old female who is pregnant is in labor. Upon examination, the paramedic observes the vertex of the head in the vaginal opening. The patient's contractions are less than two minutes apart, 45 seconds in duration, and are 10 of 10 on the pain scale. Following the next contraction, the patient complains of severe abdominal pain with tenderness upon palpation, persisting between contractions. The paramedic notes an increase in her heart rate, narrowing of the pulse pressure, and the blood pressure has decreased. No vaginal bleeding is observed. What is the most likely cause, and what should be the treatment?