What Causes Persistent Nausea, Metallic Taste, Weakness, And Breathlessness After Severe Diarrhea And Dehydration Following A Subtotal Colectomy?

I am a female age 68, chronic problems are hypothyroidism and I had a subtotal colectomy due to a mega colon. On Tuesday of this week I developed severe diarrhea (output just bile) and nausea without vomiting (Zofran helps sometimes). Diarrhea resolved yesterday but nausea continues with a terrible metallic taste in my mouth and burping when I am upright. Needless to say, I know that I am very dehydrated although I am pushing fluids. Yesterday I lost my voice, today it is slightly better (no sore throat). I do not believe I have been running a temp. What worries me now is that the weakness is keeping me sitting in a chair, but when I do get up to use the restroom or get a drink, my heart pounds and I am very short of breath.