Slow down dummy its not a race.
Bingo. This! Don't ground and pound, the rule is stimulate not annihilate (theres room for that here and there).
To the OP, its due to the bronchoconstriction,similar to an acute allergenic effect, caused by the tren, in fact that's basically what it is, as the system sees it..Inflammation of the airways! You'll feel exhausted as your almost struggle to breathe during strenuous activities..
The addition of clens will help minimize this effect, its used for this purpose medically, some inhalers work wonders (over the counter), but its short lived!
Also, Tren will induce thermogenesis, your body is literally devoting all nutrients at an alarming rate on top of energy cost/physical activity, your body is spending! Tren/clens/t3 is punishing you..
Eat,get you eats up, add more carbs!