Is there not someone with a more mature tank to look after it until it is healthy? A 2 week old tank might make it worse if the water parameters are not stable and the tank not cycled. Sadly the nennie will perrish and die
If you don't have anyone, then at least get some Seachem stability and dose according to manufacturer specs to assist in getting water more stable for the nennie.
Cover all the flow pumps in case it decided to move.
Feed it every second day small pieces (6mm in size) of hake or prawn meat. You need to keep its energy levels up to survive and to produce zooanthellae and so regain its colour again.