Pregnancy sickness at 6 months?

I am 6 months pregnant and am still dealing with severe nausea. I went to my doctor and he said he'd order some test one being checking my gall bladder. All he did was a sonogram on the baby and everything was ok. I am sick 24/7. I don't throw up but I have only thrown up 3 or 4 times in my whole life (I just dont throw up). I am really constipated on top of it all and have to force myself to eat. I'm thinking about just going to the hospital since my dr. isn't really doing anything. Any suggestions?