Worry - I often have indigestion and feel nauseous.

When I was young, I could chew and swallow stones, so I had no trouble digesting. I didn't realize I had a stomachache... but now, even with just a slight change in my condition, I seem to have trouble digesting. I feel nauseous. Could it be because I eat all sorts of unhealthy foods? Or is it because I consume too many carbohydrates? Last year, I had muscle aches like a cold, and I only took cold medicine diligently, but I didn't get better. I kept feeling nauseous and had a severe headache. I only managed to soothe it by taking digestive medicine. Do symptoms like these—cold-like symptoms—appear when I have indigestion or a stomach upset? Also, I never know when my stomach might feel bad, so I always keep 2-3 bottles of digestive medicine on hand. ㅠㅜ