I have had severe pain for over a week. had a sono yesterday morning which showed gallstone, went to er they did sono they didn't see one sent home?

Well, that's good: Ultrasound is very dependent upon who is doing the study. The more experienced sonographers are the best. Sometimes studies done on mobile units have technology issues. And sorry to add that not everyone is trained equally. It may take a third study to resolve the question. Occasionally a stone will pass uneventfully. Hope that was the case.

Passed stone?: Two thoughts. One, you could have passed the stone in between the two ultrasounds, so that it's on it's way out - if your pain has improved then this could be a real possibility. Second, one of the tests is incorrect - either the first was falsely positive or the second was falsely negative. Further testing is needed, especially if you're still in pain.