I recommend telling him about the lactation problem. You make it harder for him to help you if you aren't honest about the side effects. He will be very matter of fact when you tell him; this side effect occurs with a number of people and he is sure to have seen it before.

Are your only issues to address nightmares and anxiety? If so, how about Vistaril? It's pretty benign--an antihistamine--and can help take the edge off anxiety and also help with sleep.