Nausea with a bowel movement?

Anybody else have this happen? 50% of the time I have to take a poo I get nauseated and feel like I will throw up. Nothing helps the nausea I have taken Zofran phenergan compazine and ginger root and none of it comes close to even touching the nausea. Oh and I am constipated a lot too. Usually am constipated for a week or so and when I finally go its like it explodes I get the runs almost and I get very sweaty and I'm in a lot of pain. The doctors did a scan of the inside of my stomach and did some blood tests and everything is normal. What do you think is wrong with me? Is it Gallbladder or intestinal issues? I drink a lot of water and eat healthy. Please don't tell me I just have a sensitive stomach cuz I know its way more than that. I don't think its IBS I'm lactose intolerant but I keep away from dairy... Help!nstipated for a week or so and when I finally go its like it explodes I get the runs almost and I get very sweaty and I'm in a lot of pain. The doctors did a scan of the inside of my stomach and did some blood tests and everything is normal. What do you think is wrong with me? Is it Gallbladder or intestinal issues? I drink a lot of water and eat healthy. Please don't tell me I just have a sensitive stomach cuz I know its way more than that. I don't think its IBS I'm lactose intolerant but I keep away from dairy... Help!