I just got a call from my vet this morning and she wants me to bring Ollie in this afternoon to test for a portosystemic shunt

She went home last night and did a bunch of research and talked to the other vets in the office this morning, and just wants to rule this out as a possibility. They need to draw some blood and test the bile acid levels, so I'll know today whether he needs to go see a specialist.
Of course, I'll let you all know how it goes...I hope its nothing serious.