My fourteen year old son having flashbacks?

Well maybe, depending on how she died, he's afraid it will happen to him/you. Depression sounds most likely. just spend time with him in his room, trus me even if he doesnt respond, unless he's actually uncncious, he knows what you;re saying. just make sure to stress how much you love him, are there for him, and he doesnt have to do anything if he's not ready for it.