High energy foods? Lost appetite

Hi,
I'm 21 (5ft5.5") and while I want to lose weight and ideally be around 126lb (9st), I've been ill for about 3.5wks and my appetite no longer exists. I've heard people say 'oh I wish that would happen to me, you're so lucky', and it really make me feel awful. I was hospitalised last week for testing and while they've found nothing yet I'm returning in 3wks if I've not improved.

My highest weight was 168lb(12st) and before I stopped feeling hunger I was 158lb (11st4lb), I've gone down to 144lb (10st4lb) in 3 weeks and have lost all energy and I am now very weak and tired all the time.

So, I was wondering if there are any high energy/cal foods (in small portions) that would give me a boost and prevent such drastic weight loss. Most of the calories I've had lately have been from liquids whereas with food I have to force myself to eat.

Any suggestions for small, easy to eat food to improve my energy levels?