Wow, that looks quite a bit like an Illicium sp. Do the leaves have an odor of Anise? Any more information you can give us?
Looks like a rather unhappy Allamanda. Note the leaves apparently in whorls of 3 or more at each stem node (see leaf scars on bare stems).
I'm guessing that the ID of Allamanda is correct. After looking at photos I remembered the seller said it had yellow flowers. Now to see if I can get the plant a bit healthier!