Yes, it's a thing. Two things pop instantly to mind.

1) This is how my eating disorder began. Not liking food anymore, not enjoying the taste, sudden loss of appetite, etc. Of course, my situation was entirely different. I hadn't just had surgery. While your situation could be the same, it is best to rule out other possible things (such as side effects). Stress can be a trigger for eating disorders, but loss of appetite can also be a symptom of stress.

2) Anorexia is a symptom as well as a disorder. So, yes, it can be a side effect of medication or stress. It sounds like you do have a lot of stress in your life. Many people, when under stress, do lose their appetite. The difference between them and those of us with eating disorders is that they usually reach a point where they eat to survive. Whereas someone with anorexia may reach that point, but it will cause them intense anxiety. If that makes sense? Many medications can cause loss of appetite. It could, even, be related to the surgery.

The best thing to do is speak to someone. I am really, really worried that you had no follow up appointments. From what I've heard, it's generally best to after a surgery such as the one you had - for counselling and to check on overall wellness/health of the patient. I would try to get in contact with the surgeon, and if you can't, find someone else to speak with.