Hello, my name is***** and I have over 20 years of experience as a veterinarian. I'm sorry to hear that your little one with a history of hip problems that are being treated with Tramadol and Carprofen and Nu Joint DS daily has recently become more lethargic and is eating poorly.
I think that a recheck is in order.
She is an older girl and if she were eating well, but reluctant to move around I would think that this may be all pain related and perhaps adding another medication for pain may be all that that is needed.
But because her appetite is off and she is taking a nonsteroidal (carprofen) she does need to see her veterinarian and I highly recommend bloodwork and a urinalysis to check her organ function. I understand that your income is limited so I would ask that they run a mini geriatric blood panel. While not as comprehensive it hits the major highlights that allow us to check organ function and is often much less expensive.
In the meantime to try and settle her stomach and get her eating you can give either:
1) Pepcid ac (famotidine) at a dose of one half of a 10mg tablet per 10 to 20 pounds of body weight every 12 hours
2) Prilosec (omeprazole) at a dose of one quarter of a 20mg tablet per 10 to 20 pounds of body weight every 24 hours
These are acid reducers and may help settle her stomach and get her feeling better and hopefully get her appetite back. These can be given for several days if need be.
In a couple hours offer a bland diet of 1/3 boiled, minced, white skinless chicken or boiled, lean hamburger and 2/3 boiled, white rice mixed with some low salt chicken or beef broth or warm water to increase palatability and get additional fluids into her.
Please let me know if you have any further questions.