Gas,bloating, pain, and diarrhea may be signs of poor digestive function. This may be secondary to infection, medication use, anxiety, decreased digestive enzymes/hydrochloric acid production, food sensitivities, or dysbiosis (imbalance in the digestive flora). I have found much success in my practice after running a specific type of food allergy testing. Often people are experiencing food sensitivities and do not realize it. Although you may have made dietary changes you may still be eating foods that cause you a problem. You can find more information about this type of testing here: http://www.betterhealthusa.com/
If you have been on antibiotics, this would kill the good bacteria leading to a decrease of beneficial bacteria. This may cause an imbalance in digestive flora leading to discomfort.
Food sensitivities often present with a variety of symptoms. Conventionally they are not tested for although research indicates that approximately 95% of individuals in the US suffer from some type of adverse food reaction.
Digestive enzymes may help, however, this should be discussed with your doctor before starting. The addition of digestive enzymes (such as protease, lipase, pepsin, trypsin, chymotrypsin, etc) aids in the breakdown of proteins, fats, and sugars. Hydrochloric acid production also begins decreasing as we age which can lead to bloating. In addition, probiotics (good bacteria) may also help as they are essential for proper digestive function. Lactobacillus acidophilus is the main bacteria along with bifidobacteria. Saccharomyces boulardii is another important GI bacteria. I often suggest my patients take 9-20 billion colonies per day. Make sure the probiotic is dairy free as some individuals with dairy sensitivities may not improve with probiotics because they contain dairy products (such as lactose). In addition, omega 3 fatty acids, such as fish oil have anti-inflammatory properties that may help. Good brands include Nordic Naturals and Carlson.
Parasites, bacteria, and viruses must also be considered. A bland diet (known as the BRAT diet) consisting of bananas, rice applesauce, and toast may help. However, a certain number of individuals have difficulty digesting wheat in which case bread may aggravate the symptoms. If you believe wheat may be an issue, you should be tested for celiac disease. You can find more information about this here: http://www.celiac.com/
I also suggest repeating the pregnancy test just to be sure.
It is important to discuss testing as well as treatment options with you doctor.
If you experience abdominal pain, fever, blood in your stool, vomiting, pale colored stool, back pain, or diarrhea or if the symptoms persist, see your doctor immediately.
I hope you find this information helpful.