A Month Ago I Had A Severe Heat Stroke With

A month ago I had a severe heat stroke with temporary kidney damage, BP dropped to 80/53, I was kept in hospital for 3 days for uv therapy and also told to stop taking my 10mg lisinopril because my regular BP was 114/72 average. Last week I mowed grass on a hot day and got very hot and sweaty since then my BP has been normal some(117/79 example) low a lot ( 90/63 example) and high a couple of times ( 149/95 example ) my DR. Is on vacation and when it's low I get light headed, am I not drinking enough fluids or is there a problem with my heart? Pulse is always around 62 when sitting and goes up as high as 90 when walking around.