for you to go up and down in weight that fast its just water and glucose in your muscles,the t2 is burning up stored carbs.
When I cut hard and eat clean on a sim stack I can fluctuate 5lbs from day to day depending on how hard I train and how much carbs I eat.
what your doing is filling your muscles up with food then making them flat with the t2 ect and training.
At this point you should forget what the scale says and go by the mirror and try to add some clean mass on.