sick to my stomach

I've felt sick to my stomach all day every day for over two weeks. I have not vommited at all,  but for the first 10 days, I had diarrhea. I went to the doctor around that time and he told me that it was Gastroenteritis. He also did some blood tests which came back normal. I've been on a bland diet for a week and still no improvement. I've lost about 8 pounds in the last two weeks because I haven't been eating much. I went back to the doctor and was told to continue on the bland diet and take some over-the-counter antacid medication. I've taken it for two days but nothing has improved. I feel miserable all day and I feel like I've been sick for too long for it to be Gastroenteritis.