Hi Rach
I have Brown (Whistling) Tree frogs. Your frog has the same markings as a Whistler and the eyes are the same but Its head is a completely different shape maybe it's deformed. I had a deformed tadpole the skin on its stomach fell off and didn't regrow revealing its gills but now it's the biggest frog and is doing well. Check out my photo album and see if they match your frog hope this helps.
Luke