Rapid Heart Rate and Hypertension

I am a 29 year old female.  The other day while at work I started to not feel well.  I had taken a lasix, zaroxlyn, and potassium the night before due to severe pedal edema.  I work in the medical field, so I was able to put myself on a cardiac monitor and I had a pulse of 130 (normal sinus) and a BP of 140/100 (I normally run in the 110/70 range).  I was getting extremely winded and sweaty/clammy after just doing minor things, like climbing a few steps.  Went into the ER, and they said I had low potassium and dehydration.  I was given an IV of Normal Saline, and my BP decreased and my pulse went back into the 80's-90's.  Went home and doubled up on the potassium and went on my way.  2 days later I started to have the same symptoms, got another IV of Normal Saline which did decrease my sweatiness and decreased my pulse from 130 to 110.  Went back to the ER and they said my potassium level was fine, heart looked good.  I'm very confused about what could possibly be going on, wondering if anyone has any answers.  As for myself, I'm not in great shape, a bit overweight, but never have had a problem like this before