The reason for getting tired is Tren lowers RBC count and it fatigues you quickly having you suck wind.What you lost more than likely was water which deca aswell as sus can have you retain.I dont know about you "shredding down" thats based on more than the compounds you're taking...Diet and cardio will determine that....100mgs is NOT too low as I have ran 50mgs of Tren A every 3 days and did well...all depend on how you handle sides...