Your instinct is correct! "I am not comfortable after eating these peaches" sounds unnatural because "comfortable" usually refers to physical ease, relaxation, or a lack of discomfort in a general sense (e.g., "This chair is comfortable" or "I don't feel comfortable in crowds").
More Natural Alternatives:
✅ "I don't feel good after eating these peaches." (Casual and commonly used)
✅ "I don't feel well after eating these peaches." (Grammatically correct, slightly more formal)
✅ "I feel sick after eating these peaches." (If you feel unwell)
✅ "These peaches upset my stomach." (If it’s digestive discomfort)
Tip:
- Use "comfortable" for things like seating, clothing, or situations ("I'm not comfortable speaking in public"), but for health or digestion, use "good," "well," or "sick."
- If you're talking about an allergic reaction, you could say: "I think these peaches don’t agree with me." (A natural idiom for food intolerance)