Contents. 1  Calf rash AND Forearm rash: Causes of All Symptoms. 2  Calf rash OR Forearm rash: Causes of Any Symptom. 3  Calf rash: Causes.  Calf rash: 1  Introduction. Forearm rash: Causes.  Forearm rash: 1  Introduction. Calf rash and Forearm rash and Behind knee rash (15 causes)  Calf rash and Forearm rash and Finger rash (15 causes) Calf rash and Forearm rash and Foot rash (15 causes) Calf rash and Forearm rash and Groin rash (15 causes) Calf rash and Forearm rash and Hand rash (15 causes) Calf rash and Forearm rash and Knee rash (15 causes) Calf rash and Forearm rash and Kneecap rash (15 causes)
Gas in the digestive tract - the esophagus, stomach, small intestine, and large intestine - comes from two sources: 1  Swallowed air.  Normal breakdown of certain undigested foods by harmless bacteria naturally present in the large intestine, also called the colon.
Gas normally enters your digestive tract when you swallow air and when bacteria in your large intestine break down certain undigested foods. You may have more gas in your digestive tract if you swallow more air or eat certain foods. Swallowed air. Everyone swallows a small amount of air when eating and drinking.