fertile, but is it dead?

So far, I'm up to 15 fertile eggs (starting from Dec 1st), but I'm wondering if one of them (#17 laid on 12/2) had died in the egg?... it's shown good progress, along with all the other eggs, but when i candled it today, it seemed like it was a stand still.... I can't get a good enough pic, but it looks rather blotchy/thick/cloudy and not so veiny inside. In fact, for a while, I thought it was twins!
Should I maybe wait a day or two to check it incase it is still alive? Poor thing :/