I initially experienced symptoms of belching and diarrhea. Following a gastroscopy, which showed no issues and no presence of Helicobacter pylori, I dismissed the problem. However, when my girlfriend developed belching symptoms after we started dating, she experienced constipation instead of diarrhea. Her gastroscopy also revealed no issues. This led me to suspect the existence of an infectious disease within my body. After my son's birth, I maintained separate dining, but occasional oversights occurred. In September of this year, he started frequently belching, complaining of air being trapped in his throat. I took him to a family hospital, where a stool test yielded normal results, and no Helicobacter pylori was detected. The doctor advised continued observation, but the belching symptoms persist. I discussed this with a friend studying medicine in Göttingen, who also believes it might be an infectious disease. He suggested a parasitic examination for the entire family, including organisms like Giardia lamblia. I hope to receive assistance. Thank you.