Hi, I Recently Had An ECG And It Showed A

Hi, I recently had an ECG and it showed a slight high QT, I went to gp who discovered my be was high it was taken 3 days later and again high, I bought a monitor and over the last week it has been high mostly except for last 2 days. I had been taking 1000mg of vitamin c daily for last approx 3 months until I read that this can be connected to high bp and kidney problems so stopped them 3 days ago during which time bp was normal, I have just travelled in the car which husband and started to feel My chest was a little tight, have taken bp on arriving home and it's 143/83 again, not quite sure if this is ok or not.
Thanks