Firstly, I hope you are under the care of a Certified Nurse/Midwife or an OB/GYN who is available to answer your questions and concerns from a medical standpoint.
Constipation can be related to the hormonal changes in pregnancy and to diet changes in pregnancy either from nausea or unusual food cravings and patterns of eating. As the pregnancy progresses constipation can be due to the pressure of the uterus on the colon.
If it is of a structural nature then I suggest that you consult a Doctor of Chiropractic. Find one through the website of the American Chiropractic Association.
Easy, gentle stimulation of the bowel can be done by drinking an 8 0z. glass of warm water with the juice of 1/2 lemon first thing in the morning before eating and last thing at night before bed. I also suggest eating organic prunes daily (3-5). Either mix in with your cereal or eat with another fruit ( an apple) mixed with organic yogurt( plain or vanila-no added fruit) and add 2 tablespoons of flax seed to it. High fiber and low carbohydrates ( white flour/sugar and breads) is the key to healthy digestion, assimilationd and elimination.
All pains that you feel need to be brought to the attention of your doctor.
Enjoy your pregnancy and make it a healthy one!