I've Been Feeling Dizzy, Very Tired And For The Last

I've been feeling dizzy, very tired and for the last couple of days have been having adrenalin rushes (especially when I go to bed). I've been trying to get out for a brisk walk everyday to keep active, also limited my coffee intake. I only ever drank 3 cups at most. I don't smoke or drink. Wondering if you have some insight?