Pls help identify bump on Naso

[hillegom]

I just came home from being away from the tank for a week. The naso tank has developed a bump/parasite? just below the upper fin, on both sides.
As well, one of his pectoral fins is receding.
I have never seen this before, nor was it there a wk ago.
Please disregard the bubbles in the water, I have to address that later. And clean the glass
Thank you