My stomach gets upset every time i go out.it's becoming a problem for me because i have to go out frequently.what can i do?

Gastritis: Since your diet is primarily eating outside food, your stomach may be inflamed (gastritis). You are describing dyspepsia or indigestion. Medicines such as antacids can help; however, you need to make sure you don't have H. Pylori infection. If antacids don't help, follow up with a Gastroenterologist. Also, if you feel a burning in your chest, you may have reflux esophagitis.