One other thing:
No one here can give you the "50/50 chance" you are wanting in order to make your decision. With the symptoms you've described, you need to see a physician to be examined. Whether these symptoms are pregnancy related or something else, it needs to be addressed. It would be wise for you to find a way to scrape together the money to go see a doctor. Many areas have free or income based medical clinics. Perhaps you can check into those.
First, if you have missed a period, take a pregnancy test. If it's negative then you need to see your doctor for some blood work. As the above poster said, you should be checked for thryoid disorders and diabetes as these both can cause many of the symptoms you have described.
A change in diet can usually cause mild to severe digestive upset.
Whether a pregnancy test is negative or positive it would be highly beneficial to see your physician and have tests run just to rule out other isses. IF you WERE to be diabetic or have a thyroid disorder, for example, you would need special treatment during pregnancy.
Good luck!
Have you ever been tested for diabetes? Or your thyroid checked? Have you taken a pregnancy test at home yet?
Have you missed a period? If so, you can go to the dollar store and they have pregnancy tests for a dollar. GOOD LUCK!!! SSBD!!!!