In the medical community we sometimes like to refer to an erection or the capacity to achieve and maintain one as the "dip stick" to a mans circulatory health.

Prolonged CR or CR done to certian extremes can physically harm the body under certian conditions, including hormonal changes which can directly effect mental as well as physical health that can also lead to some of the symptoms your speaking of, but it could also be any number of other physical or phycological matters or a combination thereof.

Is the erectile disfunction postural? IE does it matter what posture or position your body is in at the time,,laying prone on your back or standing up etc? If so its most likely a circulatory problem.

Depending upon your age and other genetic and lifestyle habits (ie do you smoke or have a pre-disposition for periferial artery disease, low testosterone, low/high BP, heart disease, ED brought on by inflamed prostate, late onset diabetes etc) you may wish to consult a urologist to rule out physical vs phycological cuases and proceed from there.