Hello I am Dr. Joey. Thanks for trusting me to help you and your pet today. I am a licensed veterinarian with over 15 years of experience. I look forward to working with you. I apologize for the delay in an expert responding.
Based on what you report I am quite concerned about Lucy. My top worry is she has a uterine infection called pyometra. This is a medical emergency and you should consider having her seen on emergency today. If this is the identified problem then she needs surgery.
Another possibility is she has a urinary tract infection, which can also cause her to be very painful and lethargic. For either issue there is nothing you can do at home. She really needs an exam and some testing (lab work and some imaging such as X-rays).
I am at a point I need to know what questions you have.
I hope that the information I provided has been helpful.
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