Embarrassing Bathroom Issues: Need Advice

This is kind of embarrassing and I am unsure if this is related to any medication or maybe undiagnosed condition (I’ve been tested for Crohn’s, IBS, etc but said all clear) But sometimes I don’t have regular bowel movements then when I need to go it takes a lot out of me literally and figuratively. Like I can’t go to the bathroom sitting I end up feeling so sick and hot I usually end up having awful diarrhea bent over in a cold shower. It’s like my whole body goes into it. Does anyone else experience anything like this? It’s awful. And messy. But I feel like I’m dying and I can’t go to the bathroom if I’m sitting on the toilet. Not every time but when my body “purges” like this that is what happens. It’s like once or twice a month sometimes. I have also been monitored and tested for gluten or dairy intolerance and all clear with that, too, I guess. Am I the only one who experiences these episodes?