no appetite

I've been having less and less of an appetite past few days 30 weeks currently and if I force myself I get very nauseous to where I almost throw up or I do I also been having abdominal cramping and back pain with some contractions that are painful here and there but I chalk all that up to Braxton hicks or because it's twins this is my first time with twins I don't remember any of these with my singletons anyone else experience loss of appetite