Appendicitis, Stomach Ulcers?

Not exactly sure but I have felt like after I would eat I feel as if my body is churning, it feels thick inside, like it is not digesting and makes me feel like throwing up, but not to the point of vomiting. After I eat, the only thing that made me feel better was lying down for hours until this pain would go away. I also feel like I have hot/cold sweat and shivers. Overnight I felt the chills almost as if it was a fever but I came to check my temperature and it was fine. I'm not too sure but I have put my baby first over me, but during the time after eating I always carry her when she cries and she is 17 lbs already. Sometimes I may lack eating I wait a long time to eat my first meal of the day which is at most 12 hours. Sometimes I feel gassy but it doesn't hurt. My only concern was today I felt queasiness while I was eating, very lightheaded feeling as if I wanted to faint while I was eating. Not really sure what this is so please help me. I typically eat 2-3 times a day. I took a pregnancy test and I'm not pregnant. I usually just feel so sweaty weak that I can't help but just lie down.