Well, the weight doesn't tell us anything without knowing your height. If you're only 16, exactly what work are you doing? Aren't you in school? As to the rest, if you don't eat, you don't get the proper nutrients. But you haven't said if you've seen a doctor.
So sorry you' ve had these problems.
You need, imho, a battery of blood tests (including thyroid) and a good examination.
With the numbers you approximate for your weight loss, your height doesn't matter. And your weight loss is not profound.
What is profound is that you need an accurate diagnosis.
Hope you're better quickly....
You should see a doctor for further workup and evaluation. Laboratory testing for patients with unexplained fatigue includes complete blood count (to rule out anemia), erythrocyte sedimentation rate (to rule out inflammatory state), chemistry panel (to rule out liver disease, renal failure, protein malnutrition), thyroid function tests (to rule out hypothyroidism), and pregnancy test (if indicated). For more info: https://www.aafp.org/afp/2008/1115/p1173.html
I had a situation that involved my being fatigued and lethargic and my doctor determined that my caloric intake was not high enough for my fitness level. That was a super long time ago, ha ha. But I was basically dieting while increasing exercise. His recommendation was more food or less exercise.
Since you are only 16, I am going to figure you have not been to see a doctor. You might be scared of what the doctor will say or what your parents will. I understand this fear way to well. I must tell you it is better to get seen and face what might be said. Then to wait and not know what might be said.
My daughter is 18, but shortly before she turned 18 she became very heavy set. She looked pregnant, and had similar sxs of morning sickness. Her mom accused her of being pregnant which led to her hiding what she was feeling from everyone. To make a long story short, she finally couldnt take the pain and sickness no more and told me and her grandmother. Her grandmother took her to the ER and we found out she had been suffering from Colon Cancer the whole time. The tumor had grown to be the size of a basketball, and It had spread to a few different areas.
I know you are losing weight and the sxs are different, but the morale of the story is it is better to go get seen or speak to someone about what you are feeling, then to hide it. Please, let us know what you find out.