Vomiting started suddenly, with frequency

Poor Meep. We drag her off to the vet on Thursday, and though she's
fine she was a bit down that afternoon - but normal by night, and normal
yesterday.

Today, she got a few minutes out in our yard - she's mostly an indoor
cat but spends hours out there in summer. Wasn't interested in hours,
so she was maybe out there for 10 minutes.

Some short time after that, she vomited a small amount of food, mixed
with a little bit of hair. Normally I'd have expected her to throw up
grass after being outside. We cleaned it up, and didn't think too much
of it (she's rarely thrown up food before), and went out.

We came home, and shortly after, I heard her retching, and she threw up
more food. At that point we found two more piles behind the table - one
was still warm. It seems to be just her food though.

After maybe another half-hour, she threw up again - this time just
brownish bile. She's never vomited this much before - 4x in perhaps a 7
hour period.

Called the night tech at the clinic, she said take away her food, and
call if she's still retching in the morning. Perhaps feed her a bit of
chicken if she hasn't tossed any more.

I checked a book I have, it said take food away for 24 hours, then
suggested the same bland diet. That will be problematical as she won't
eat any human food except Parmesan cheese, shrimp and tuna - but not the
chicken that's suggested. Also suggested kaopectate, but we don't have
any and it's 11:30pm here.

She hasn't tossed again for about an hour now, but she's needy and
uncharacteristically hanging out next to me in the computer room. She
did look a bit distressed after the last session, but then I am too when
I'm tossing up everything I've eaten...

I'm worried that she could have picked up something outside, since this
is very unusual for her, and it started after she'd been out. Now, for
only 10 minutes... but could a foreign body cause this sort of thing?

AFAIK she only eats grass, and there's plenty in her usual spots so I
can't really see her getting into anything else, but we do have roses
that I was clipping yesterday so I wondered if she could have got a
thorn on her paw, then ingested it? What would the symptoms be if she
had eaten a thorn? I can pretty much rule out poison, there's simply
nothing like that in our yard, and if it was a poisonous plant I'd think
she'd have gotten into trouble long before this.

I'll definitely call the vet in the morning if she's still retching, but
I'm not sure how I'm going to sleep tonight, worrying about her.

Any help is appreciated.

jmc