One of my piggies, Truffles, started making a strange noise yesterday. It sounds like a bullfrog croaking. It comes and goes. The only thing that I have done differently is feed them Wheatgrass for the first time yesterday morning. I noticed it yesterday afternoon. Has anyone ever heard this sound before? Could it be a URI? He is eating and drinking just fine and has no noticeable signs of drainage around his nose. Thanks in advance!