There are several different blood tests, and the most likely illness will vary according to which test is abnormal.
The most common condition that can cause abnormal liver tests, abdominal pain, nausea, vomiting, and diarrhea would be gallbladder disease from gallstones. However, there are many other conditions that may be more or less of a concern, depending upon which test is affected.
Generally speaking, an ultrasound of the liver only needs to be done urgently when someone is more severely ill. If you are having more severe symptoms, then it would be appropriate to be seen at a hospital. Even with gallbladder disease, most cases can be managed over days and weeks, but someone with more severe symptoms ,may require emergent care.
So, if you can find out the specific tests, I can make more specific comment upon the most likely condition that may be present. As for timing, if you are having severe symptoms, then it would be appropriate to be seen at a hospital, but otherwise it would be OK to wait until the 20th for the ultrasound.
If I can provide any additional information, please let me know.