Bless you for taking her in!

I'll never use feed store "veterinary" products again.

I very nearly lost a cat using a wormer from a feed store;
those things are manufactured in other countries & labeled as appropriate for cats even though they're extremely toxic.

I my own self would take her to a free or low-cost clinic;
check with your local shelter, rescue groups, google, etc, & don't give up if the first one tells you that you'll have to bring her to their place & pay a high price.

The SPCA of Texas is famous for doing that, & it just isn't true;
there are all kinds of other options.

Take care!