I too can't see the picture.
Yes, it is possible for allergies to pop up on cats during their adulthood. Did the vet mention your cat having Eosinophilic Granuloma Complex?
What are you feeding your kitty? What type of bowl are they drinking and eating out of?
Cat maid to:
Jasper, male Ragdoll ?? (approx 10 yrs)
Rose semi feral, a cpietra rescue, female tabby (approx 7 yrs)
Sweet Pea RIP (2004?-2014)
Puddles RIP (1996-2014)
Snowball RIP (1991-2005)
In a cat's eye, all things belong to cats.-English Proverb
“While we are free to choose our actions, we are not free to choose the consequences of our actions.” Stephen R. Covey