Finally i figured out that drinking coffee is what cause me diarrhea and makes me feel good and maybe a bit nervous, is that normal?

Caffeine is a drug: Caffeine can have beneficial effects on alertness and aspects of health, but it can also cause problems, such as insomnia, nervousness, muscle weakness, dehydration, nausea, vomiting, and diarrhea. It's important to drink coffee (contains caffeine) in moderation and to be aware that caffeine is found in many foods and beverages. Caffeine taken later in the day can disrupt sleep. Don't overdo it!