What can I do with Mom with dementia while I'm at work?

I am my moms primary caregiver. She is 84 and is in excrucating pain which her doctor is unable to help because she has dementia and the stronger pain meds make her dementia worse. My actual question is that I need to get a part time job and that would mean I have to leave her. She cannot really be left alone. Is there a place that would let someone care for her while I am at work. We do not have any money so it would have to be free. Thanks