I have endo, and I used to get that pain
too when I had to make a BM. The other
stuff by itself could have been easily
written off as just PMS, but idk, that
first symptom sort of jumped out at me.
I used to be in severe chronic pain from
endo, but I changed my diet and now I feel
much better. I cut out chocolate,
caffeine, red meat and lowered my carb
intake. I use one of those online food
diaries so that it's easier to track
exactly how much of everything I'm
getting. I also quit eating fast food,
and try to eat mostly fresh, real food and
not as much processed items (like tv
dinners etc. convenience foods are loaded
with stuff you just don't need). Changing
your diet could go a LONG way to managing
your endo if you have it.