Have you been having any other different symptoms besides just loss of appitite?
Just loss of appitite doesnt come from depression...usually more symptoms are more prominate...A few years ago my boyfriend dumped me and I couldnt eat for about a week. This was before depression hit me...also a friend died in a car accident and i couldnt eat for sooo many days. It wasnt necessarily depression but it was just shock and pure sadness. Depression is extreme sadness and loss of interest over a long period of time. If this continues and with other symptoms maybe talk to a psychologist or just your doctor.
Yes definitely go see a doctor or a counsellor if it's easier (doctor will likely refer you to a counsellor anyway, but possibly not). Even if it isn't depression they may be able to give you some tips as to how to avoid depression because times like this make people more vulnerable for it. Last year my boyfriend ditched me (pretty cruelly) at examtime and continued to be a real **** to me and I lost 10 kilos. I was definitely depressed (as indicated by some pretty clear other symptoms). This year I've had another major depressive episode and gained 10 kilos instead. Not cool. Can't fit half my clothes.
But yes, changes in appetite is a classic sign of depression, although of course that doesn't necessarily mean that you have it. It could mean that you're just having a hard time (which is the best you could expect, under the circumstances).
It's really worth trying to force yourself into a healthy eating routine despite your fluctuating appetite, because all those vitamins and carbohydrates and energy etc really do make a difference to your mood.