Hi...this is the very reason why and how I stumbled upon yorkietalk last year!
One week after I got TJ, he would have his episodes (as I call them)...
He didn't want to eat and his tummy area would make all these strangle loud gurgiling noises, then after awhile of him just lying around he would poop but it would pretty much be just mucus...and then he would be fine and starving!
I would suggest going up the search button here at Yorkietalk...
type in: mucus poop
There is tons and tons of very helpful information in past threads!
You can PM me if need to talk more