What Causes Lack Of Appetite Post A Appendectomy?

I had my appendix out in september 2015. Right before i had the surgery, i weighed 251 at 5 9. It is now june of 2016 and i now weigh 195lbs......i have actually completely changed my diet to a very UNHEALTHY lifestyle. Not by choice....just all of a sudden. I now really only eat at night (10pm-2am) sleep 8-9 hours sometimes more and dont eat till around 10-2am, i was told i am overheating at night (even during winter, which is new news to me). I drink plenty of water but for my meals during the day, all i drink are iced capps from Tim Hortons.....i live in NY lol Anyways.....idk whats going on with my body and it all started after my surgery and what i crave and what keeps me going now. Maybe i am just depressed haha (not funny). I dont know. Im not complaining about my weight loss, i just know i cant keep eating like this....i will die soon, right?