Jen,
what do you think is the main problem? Which pain -abdominal or chest- is worse? Do you think they are connected? Have you experienced chest pain with your tachycardia in the past?
There are many causes of chest pain - musculoskeletal, cardiac, gastrointestinal, lung, psychiatric and referred pain from other areas of the body, such as neck or gallbladder. So, your abdominal pain and chest pain might not even be related.
I have some issues that also include abdominal distention and sometimes pain. If you haven't had one recently, you should probably schedule a gynecological exam to cover all the bases. Female reproductive system disorders or abnormal growths can result in these types of symptoms. A quick, inexpensive ECG would also be a good idea.
flowergirl