Pain After U/S?

D • Pregnant with our first. Terrified and excited. Due Sept 2016.
Have any of you had intense stomach pain after your ultrasound? Just had my 12 week appt and about six hours later have crazy stomach and back pain. Could it be from the full bladder or the U/S tech, or just a weird coincidence? Also, what do I do to relieve it? Warm bath?