My corgi has diarrhea, leaky stools, and pale poop. What to do?

The reverse sneezing and the diarrhea almost certainly have nothing to do with one another, as reverse sneezing is not even a pathology unless it is happening constantly and having an effect on breathing. As far as diarrhea goes, I would say the first thing worth trying is fasting Bee for 24 hours. Then, put her on a bland diet or boiled skinless chicken and / or hamburger with rice for 2-3 days. See if this normalizes thing. You can also try and collect a fecal sample that can be submitted to your veterinarian for parasite analysis. They will provide the appropriate dewormer should that be needed. If the diarrhea continues in spite of the dietary change or it starts to get worse (or any other clinical signs develop), an exam by your vet will likely be required to get down the cause of the problem. Hope this makes sense.