No, 8 mm is not a small stone and you will definately not have fun should it decide to take a trip. What you felt Sunday was likely a smaller stone that did pass through your cystic and bile ducts. Very thickened sludge passing can cause temporary events as well. Does your doctor plan to simply watch the 8 mm stone?
Try taking a supplement called Jarrow bile acid factors, people in Amazon com have found a lot of relief wiyh their gallbladder or GI problems.
You might want to talk to your doctor about a couple of medications known to help with at least reducing the formation of gallstones by modifying the bile composition - and there is some limited evidence that they can help dissolve stones in a subset of patients. The medications are: chenodeoxycholic acid and ursodeoxycholic acid (Urso for short). Urso is used for a number of different biliary diseases, so its effects on patients are well understood. Also,most doctors will tell you that hepatobiliary supplements are at best a waste of money, and some many not be good for you. Always good to discuss things with your doctor when they provide you with simply a report, without touching base on your options. Take care.
Went to the follow up and the Dr said that the stone is too big to really worry about it getting stuck in my bile duct and he doesn't think the Sunday incident was gallbladder related. He says gastritis or duodenitis most likely. I guess we will see.