Hello, you are through to Dr Linda, a UK based vet.
I'm sorry to hear your Frenchie has not been well and appreciate your concern.
Nutracys is a nutritional supplement that would not be expected to cause any adverse reactions.
Metacam is generally well tolerated but can cause signs in some. According to their data sheet:
'Typical adverse reactions such as loss of appetite, vomiting, diarrhoea, faecal occult blood, lethargy and renal failure have very rarely been reported from post-marketing safety experience. Very rare cases of haemorrhagic diarrhoea, haematemesis, gastrointestinal ulceration and elevated liver enzymes have been reported from post-marketing safety experience'.
The symptoms you have reported would not be what we would expect so they may be unrelated. I would wonder if her symptoms would be more to do with the humid weather, or perhaps the pain/stress of her cystitis.
We should stop Metacam if a dog has vomiting, diarrhoea or goes off their food.