Hello Pagie,
A couple things I would advise to check with your doctor about. One your gallbladder. This could be a result from gallstones. I had my gallbladder out many years ago and I had major attacks with the same symptoms you have listed. NOT a great feeling. They wont kill you it just feels like it.
Two: Anxiety attacks. Even if you have gone your entire life without having an issue of anxiety it is an enigma that haunts women mostly. I have had this issue as well for many years(under control now thank goodness) and first I thought I was having a heart attack!.. SCARY! but the attacks (for me) were much the same as how the gallbladder attacks were. The attacks for both the gallbladder as well as the anxiety will come at any time and be triggered by anything.
I would check with your family doc on these things.. It could be neither of those things but wouldnt hurt to ask about those. Now days the gallbladder surgery's are done laprosopically so minimally invasive and Anxiety issues can be treated in many different ways. Some without medication of anykind. However, there are some medications on the market now that can be used to treat Anxiety that are non addictive and dont have the side effects that some of the others do.
I hope this helps. Good luck to you!