Looks like all your damage is coming from Pheromones
Stolen from icy-veins:
You must understand the debuff that Garalon applies, since this is the key to the encounter. When engaged, Garalon will cast Pheromones Icon Pheromones on the player that pulls him. He only casts this debuff once, but it will remain active for the entire duration of the fight. Pheromones has several effects.
While Pheromones is active (so, always), it will constantly deal a small, yet increasing amount of Nature damage to the entire raid, every 2 seconds.
Garalon fixates on the player who is currently carrying Pheromones, and moves towards them.
The player who is currently carrying the Pheromones is affected in two ways.
They receive a stacking debuff, called Pungency Icon Pungency, which increases the damage that Pheromones Icon Pheromones deals (to all raid members), by 10% of its base damage, per stack. Pungency lasts for 2 minutes in 10-man, 4 minutes in 25-man, and 20 seconds in LFR. A new stack is applied every 2 seconds, and in LFR, the stacks are capped at 20.
They leave a trail of damaging void zones behind, called Pheromone Trail Icon Pheromone Trail.
Pheromones can be passed on to a different player, simply by coming into contact with them. This is to say, when the player currently carrying the debuff comes within 2 yards or so of another player, the debuff will move to the new player.
The damage of Pheromones is reset to its base value each time the carrying player changes. So, for example, if the player currently carrying the debuff has 10 stacks of Pungency, then Pheromones will deal 100% extra damage to all raid members. When the debuff passes to a new player (who has no stacks of Pungency), Pheromones will deal its base damage to all raid members (including to the player with the Pungency stacks). Therefore, the damage that the raid takes from Pheromones will have a predictable pattern of low-medium-high-low.
If, however, a player who already has stacks of Pungency takes the debuff when it is passed on, Pheromones will deal its damage based on this player's stacks of Pungency.
If the player currently carrying the debuff dies, the debuff will remain on their corpse, and its number of stacks will continue to increase. If this happens, someone has to move over to the player's corpse and take the debuff from them just as they would if the player were alive.