This could be a uterine infection or a bladder infection its hard to be sure from your description.
You can read about pyometra here
http://marvistavet.net/html/body_pyometra.html
and about bladder infections here
http://www.thepetcheckup.com/works/screen/urinary_bladder_disease.html
She does need vet care to find out what is going on and to treat it.
www.carecredit.com may help you finance a vet visit. Your vet may let you do payments if you ask.
And this site may help you find financial aid
http://www.uan.org/lifeline/resources.html
Hope this helps you!
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