Could be very serious I'd get to a vet asap.
Originally Posted by Mijo
only dry food, highish standard
Kitty's should be getting wet as the main meal and dry only as snacking food imo. Also "high standard" can mean expensive crap. It's wise to research the ingredients to make sure it's not mostly filler, most of it is. Lots of good advice in the food forum here. Good luck.