well first of all if you are drinking out of a coffee cup that is about 10 oz.
which is alot of senna tea.
you should only be having 4-6 ounces. (which is about the size of a cup that you set on a saucer)
one senna tea works for me 2-3 days.
you dont have to have the tea everynight.
you should be having BMs everyday.
try skipping the tea and doing it every other night. and making sure you drink a lot of water after your tea.if i ever felt a tinge in my guts i would start drinking water. i never got cramps this way. try it.