Living with BPH/Enlarged Prostate

Hi can any one give me a clue at to what might be wrong with my condition and what to do about it. I am 62 male in very good health, just completed the London Marathon, but over the last 3 years i have been suffering from spasmodic urine retention. When I say spasmodic i mean I can go for about a year with no problems then out of the blue, always between 2-3am i cannot pass urine. Before i go to bed no problems, but come the bewitching 2-3am nothing doing. By 5-6am my wife is taking me to A E to have a catheter fitted. Release the pressure, the bag fills to about 700ml, and I am back with the living. The use to send me home with the catheter strapted to my leg but I found the pain of wearing it by the next day I was into the doctors demanding they take it out. With it removed back to normal, peeing when I want to with NO PAI, NO BLOOD, NO DRIBBLES, just good aol fashion peeing. everthing is fine untill it happens again, and its the same procedure all over again. I have had just about all the tests that my hospital can perform on me, with nothing to indicat that there is anything wrong. All blood samples Ok, PSA constant over the last 3 years, Blood test just before the catheter was inserted came back 100% clear. Ultrasound of the bladder showeed good.

Neither my doctor or the specialist can give me an answer. They have put me on TAMSULOSIN AND AVODART to try to sort it out with out to much success. I do alot of long distant walking 200-800 miles out in remote areas. No people, no phones, no transport. and am getting alittle apprehensive about being so far from an A E deptment.
CAN ANYONE OUT THERE PLEASE HELP
kind regards Haydn