Falling flat in the bedroom could mean trouble out from under the sheets too. Erectile dysfunction (ED) affects millions of men, both young and old , with between 30 and 50 million experiencing difficulty getting and keeping an erection — in fact, one expert told The Post we’re headed for an “ epidemic of erectile dysfunction .” But being in a not-so-hard place could mean more than a dissatisfying sex life — trouble rising to the occasion could signal some serious health issues in the future,