I Have Been Constipated And Feeling Bloated In My Lower

I have been constipated and feeling bloated in my lower abdomen for 3.5 days now. It started with some nausea in the afternoon and a migraine. Now I can't eat very much before I feel extremely full and then I am burping a lot for the rest of the day. I tried a laxative yesterday, but that hasn't helped at all. It seems the worst at night, especially right before I go to bed.