Montresor,
I have really no idea---but.....
I have known guys who have been totally worn out and it has taken days, a week to recover. I suspect this is what you are doing. I suggest you try an experiment. Do not ejaculate more than once a day for two weeks. See if this problem still persists. If it doesn't and I suspect it won't - then try no more than two ejaculations in a day for two weeks. Keep working up to more until you find your breaking point.
I think you are pushing yourself too hard and your body just doesn't hav ethe resources to recover as quickly as you wish. Fewer ejaculations more often I think would be better than more ejaculations less often ----- but see what you think.
Susan