What is the tank size? Temperature? Is it cycled? Water parameters? (pH, ammonia, nitrite, nitrate)
What have you fed him? How much? How much aquarium salt did you add?
I know you just got him recently so it's probably not something you did but these are still good things to know. It looks like he's pineconed.
I think epsom salt sometimes helps with this but I don't know the dosage. Really hope someone comes along soon to help you, he's beautiful.