Young tree help

[Mister]

A few months ago I bought a new tree, it was about 3-4ft tall and did very well at first. Now, the leaves at the top have started falling off, and I can't see any new ones coming out. Not only that, but new leaves have started growing only a few centimeters from the ground, at the base of the trunk. Are these new leaves the reason for the growth at the top to have stopped? Should I prune them?

Thanks for any help.
This is in the southern hemisphere, and the tree is a Acnistus arborescens, if that helps.

[bullthistle]

Normally when sprouts come from the base it means the tree is basically dead and it is trying to re-establish itself. If that is the case cut back the main leader and chose 2 or 3 suckers to form the new tree but it will be awhile before it grows to 5'.