i have had an IUS fitted for 3 years, 2 weeks ago i started with constipation (my diet hasnt changed so for no reason that i can see) and my left nipple is very sore and my left breast is also very tender (although not as much as the nipple). my right breast is fine. to look at my left breast seems slightly lower which is something i have never noticed prior to this problem. I have 2 children, youngest is 3. Any ideas?