Poorly Cats

[AvengingGerbil]

Both my cats (tabbies, 13 years old) are losing whole clumps of fur, but only on their backs, towards their tails.
Also, both are vomitting a lot - but it doesn't seem to be fur they are upchucking, just food, grass and slime. (They come in to the house from the garden to do this and find a nice piece of carpet to sick up on, so I have intimate knowledge of the contents.)

They went to the vet for their annual checkups a few weeks ago when the fur thing had just started, and the vet didn't seem worried about it - suggested mites/fleas, which we have treated them for (even though I don't think they had them, as any flea within a five mile radius comes and bites me first).

Do you have any ideas as to what might be going on, or should I just return them to the vet forthwith? They seem pretty happy in themselves.

Bump - any cat people out there?

Trying again for the evening cat-people...

did the vet check for worms?

FOod allergies can cause skin problems. Mine is sick if he has maize.

Thanks for answering! No sign of worms. I hadn't thought of allergies - we have massive lime pollen issues going on here this year, maybe that's it.

Their food hasn't changed (unless the recipes have been altered, I suppose).

I guess I'd better see if the vet can see them this week.

Does it appear that the fur has fallen out (and left smooth bare skin underneath), or does it look like they've chewed the fur and the skin is weepy underneath?
If they've been chewing, check the skin around the bald bit. Possibly it's a flea bite allergy, or a reaction to an irritant in the garden.
Possibly a neighbour has sprayed something on a plant, and the cats have rubbed up against it, causing irritation on their hind quarters?

I've got a cat but she hasn't lost clumps of hair like you describe. However I had a dog who had a flea bite allergy. Most summers she would get a flea bite, and in a very short space of time she had chewed a bald patch near her tail. The skin underneath was v red and weepy. The vet would give her an injection of (I think) antihistamine and she'd be fine after that.