Sometimes i get constipated and when it finally releases it is diuretic and i get nausea, abdominal pain, low bp, and sometimes vomit. these episodes lead to passing out due to bradycardia. obviously it's not normal. what do you think i should do?

Your statement, especially the first sentence, does not make sense. Did you mean you use laxative (not diuretic) and then had side effects? Passing out due to vomit and retching is caused vasovagal syncope. Avoid the laxative which precipitates the GI symptoms. Prevent constipation with good hydration, increased activity and eating foods with high fiber and taking stool softener if needed.