Severe, severe anxiety

Question
My 4 year old beagle shepherd mix is having such extreme anxiety attacks during the night that he has kept me up now for 5 nights in a row from approx. midnight until 7/8am. It is uncontrollable panting and nervousness that makes him literally climb on top of me...I will try to calm him as he is on me, but he can never be close enough, he starts climbing on top of my head and clawing me to get "closer".  I often have to cover myself, including my head with a blanket so that he doesn't get me in the eyes. The biggest problem here is that I have no idea what is triggering this behavior.  I've had him for a year and a half, he is a rescue dog that has been through a lot.  He is missing his right eye due to being attacked with a machete, he has no ball joints in his hip sockets (had surgery to remove them and replace with scar tissue) has been burned and shot twice with some sort of gun that fractured his pelvis, he also has a fractured femur.  He also had heartworms. I know this sounds like it would be obvious why he is anxious, but before this particular instance he was happy go lucky and now, I just don't know.  His anxiety at night started last July, with a couple nights of this and then he'd be fine for another 2 months or so, now it is just over the top.  I have to leave our bedroom and sleep on the couch as to not keep my husband and my other dog up.  My three year old son wakes constantly during the night from all the commotion (he's up with me right now as I'm writing you).  I have been to my vet several times, we tried sedatives, now he is actually on prozac, which he just began 4 days ago.  I just don't know, I've tried everything and am so tired that it is hard to function during the day at all.  My husband and I take shifts now so that I can even sleep at all.  I've read up on all behavior modification needed along with his meds and all articles on anxiety, however, the whole problem is that I have no idea what the trigger is.  I am dedicated to being here for my dog no matter what and it is just breaking my heart to see him in so much agony.  Any advice will be so truly appreciated, thank you!

Answer
With a dog like this what you will need to find is a special trainer that has dealt with dogs with anxiety and can actually come to your house and work one on one with him,and it's better for a trainer to see these problems as they can find the best way of solving it. And it would be best to call a number of trainers,and some trainers may recommend another trainer that is more skilled at this type of problem. It will take time and money but good trainers can work miracles on dogs like yours.