I have a constant pain in the middle left hand side of my stomach?

See your doctor if: you've had this pain for awhile as it can be gastritis, and depends on what you eat, your diet, your hydration, other medications you're taking or supplements affecting your stomach. You don't want it to develop into an ulcer, so it's best for you to get an abdominal exam during your physical, and have this evaluated deeper. Good luck!