I've tried not to show a phobia but try to interpret what it is and what it does to a people with a phobia.
It's a fear that is extreme and let's the person helpless.
So, although it's not fully understandable the person on the drawing is naked and it's in a fetal position, so it seems more fragile.
Phoibia it's also a fear that borns and grows in our head, in our mind. And it does not gives us good thing so it's a dead tree growing in his head, with no fruits or leafs to give.
Enjoy it! :)