For over a moth now my cat has been doing the hairball dry-heave late at night, and only ever bringing up clear fluid. While I can find lots of sites stating give him butter/mineral oil/etc to help prevent cats ceveloping hairballs, I can't find anything on this scenario. I presume he has something hairball-like that he cannot digest or spit up, but how can I help him? He eats a raw diet with added salmon oil and seaweed (for his teeth) plus some Orijin (healthy high-protein) dry between meals. He loves butter. Nothing makes a difference for this.
Could it be something else? How do I help him get this obstruction out?