36 weeks and 3 days pregnant feeling and seeing stomach swelling?

ok so im 36 weeks and 3 days pregnant with a boy and this is my first pregnancy. the top half of my stomach is swollen and it is very noticeable, its tender to the touch i know he is lower down there and not in the swollen area. i was in a wreck a year ago st Patrick's day and im pretty sure some intestine damage occurred because ever since the wreck my bowls have been very ab normal. i have been to the doctor just for that like 15 times and all they tell me is miralax plenty of water and no laxatives. but i have gone up to two weeks with out a bowl movement from time to time. now i have been with out a bowl movement for about three days and this swelling is happening can some one help me please?