There are multiple potential interactions.
In addition, spironolactone and lasix can raise her digoxin levels.
She is at risk for dig toxicity, and this would account for many of her symptoms.
She needs to be investigated for cardiac problems as well as arthritis.
I suggest you take here to a geriatrician or internist.
If that is not possible, you should have a serious conversation with her GP about a cardiology consultation.
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