Hi. I see you are new to our community. Welcome! And good question. As you may know, we cannot offer medical advice or diagnostics over the Internet, for your own safety of course. While I personally have not experienced pericarditis, I look forward to hearing from community members who have experienced this to hear their thoughts on this this important topic. That said, I do have something to say about your inquiry. Generally, diarrhea is not a typical symptoms of pericarditis -- I believe the main symptoms are chest pain or tightness, shortness of breath, and/or fatigue. That said, we are all unique and may experience conditions like pericarditis in different ways. If you are experiencing this or any other symptoms, it may be best to talk to your doctor, who knows you best. What do you think? John. community moderator.