You shouldn't have got the fish if it is not 100% right.
You should have quarantin it for at least 2 weeks to de-stress (if there is such a word) it and to adapt to your feeding and waterchange routine without being hassle by other fish.
Discus with gill flukes will be dark, clamp fins, hiding, swollen and flare gill plate , and all those mention by Jeff and Sharn.
Ron