I Have Been Having Episodes Of Duzziness And Have Blackout

I have been having episodes of duzziness and have blackout once, my partner has said my lips changed to a very white colour. Im always tired and have been to the doctor numerous times. I have just been recently getting swollen legs so he put me on fluid tablets. I also have had a blood test carried out for my heart but came back normal i am worried because when i blacked out i had no warning except that i was hot so i was in a chair outside in the breeze, my partner found me slumped over in the chair. Please advise what i should do as i have to drive everyday and that worries me to because i have come close to blacking out behind the wheel