Hello, thank you for putting your trust in our site, my name is Dr.Soliman and I will be glad to answer your question. First, pregnancy blood test will get accurate results within 7-12 days after conception, so we have to exclude the pregnancy option. Second, GERD is characterized by a number of symptoms that include dysphagia which is difficulty swallowing, sore throat with sour taste in mouth, regurgitation of food and sour liquid (acid reflux)and what you feeling is just nausea after any meal, so I don t think GERD is the rightful diagnosis, the impacted stools in colon might affect the peristaltic movements of the entire GIT and any food enters the tract cause discomfort and upset and in your condition nausea, the endoscopy suggested by your doctor is considered a great diagnostic tool to identify the pathology causing this chronic nausea. Try using metoclopramide 10 mg 30 minutes before each meal 3 times a day for regulating the gastro intestinal tract peristaltic tone and prevent the nausea as possible, and also try to eat small full of fibers meals, and avoid fried and fatty meals. I hope this answer fulfill your query and if you are satisfied with the answer please consider giving 5 star rating , and feel free to ask any additional questions and I will gladly help you with an answer.