It is not like that there is something in oreos which can do this to any one. This can be because of indigestion
, which may be causing this type of cramps and diarrhoea
One important thing is there that the oreos which you ate may be expired or contaminated with some thing and this lead to some infection which is causing this problem.
Although what ever is the cause, now it is important for you to control your diarrhea
and try to maintain your hyderation with using lot of water and also include ORS
(oral rehyderation Salt). This will help you in maintaining your hyderation and minerals in the body.
If the severity is not very high than you can keep taking ORS and household items to maintain your hyderation and this will be controlled and if it is really making worse and further worsening than I would suggest you to see a doctor and he/she will prescribe you medication for cramping and diarrhea according to your condition.
Thanks and take care.