Broccoli contains sugars just like beans do which can make the broccoli hard to digest for some people.
Some people can easily digest broccoli while other people have a harder time with digesting broccoli.
Not only is broccoli high in that same sugar as beans they are also high in fiber which some people also have a hard time digesting.
You could also be allergic to the broccoli and it just doesn't agree with your stomach.
Raw broccoli is also usually harder to digest than cooked broccoli.
Broccoli can upset your stomach especially if you have an allergy to broccoli.
Some people are allergic to broccoli and other green vegetables and they cannot digest the broccoli properly.
Other people may just have digestive problems and naturally just cannot digest the broccoli.
Cruciferous vegetables, like broccoli as well as cabbage, have the same sugars that make beans gassy which can make the broccoli as well as cabbage hard to digest.
Raw broccoli tends to be harder for some people to digest than cooked broccoli.
If you continue getting sick from broccoli then it would be best to let your doctor know as you could have an allergy to broccoli.