Depending upon your age, your family history (any close relatives ever have breast or ovarian cancer?), and findings on your physical examination there are a lot of reasons to have the symptoms you are describing. Cancer is the worst possibility but is not the most common answer.
A basic Xray will not help too much, nor will basic laboratory tests. Also, although a lot of well-meaning people believe that CA125 is a good screening tool for ovarian cancer it most definitely is NOT!! It can be normal in the presence of cancer, or can be abnormal for lots and lots of reasons that are not cancer. A general recommendation about how much it might help in your situation is impossible to tell from the information you provided.
If you are experiencing continued symptoms like you describe, then further evaluation is prudent. This may include ultrasound, CT scan, sigmoidoscopy or colonoscopy. You need to discuss what is next with a trusted doctor, and, if you are not satisfied remember that a second opinion is always reasonable. What you describe is very general and really requires your doctor(s) to piece the information together carefully and logically step-by-step.
Best.
Dr Steve (www.gyncancerdoctor.com)