Pantoprazole is appropriate if your mild chest pain and gas are caused by acid reflux. However, it will not treat your loose motions. To manage the loose motions, the most important step is staying hydrated using Oral Rehydration Salts (ORS). You can also consider a probiotic to restore gut health. Because you are experiencing chest pain, even if mild, it is crucial to be evaluated by a doctor to rule out any underlying heart issues. Please avoid further self-medication. If your chest pain worsens, spreads to your arm or jaw, or is accompanied by shortness of breath, seek emergency medical care immediately.