light headed while shower????

 I have problems with showers since about 2008 when I was diagnosed with atrial fib. They dont make me feel dizzy, but I do get weak. yesterdays shower made me feel like I was going to pass out when I was getting dressed.  Ive been feeling weak and tired though even when I am not showering and am out of breath when I get to the top of our stairs in our apt.  I dont know if my iron is too low.. I will ask at my dr apt on tues to get it rechecked.