I definitely agree with everyone else.. you need to get him solid and trusting on the ground. Work out these lunging issues. If you need help with him because he's strong or whatnot, definitely bring a trainer into the mix and get help from them! Focus on halting when immediately asked, and standing still and relaxing. Work on teaching him to lower his head on the ground and release his jaw by sticking a finger in the corner of his mouth (like you do to bridle him.) My horse was helped so much by me taking time to make sure he was relaxed. Also, take things slow.. and always end on a good note :)
I wish you only the best of luck! You'll get through this!