There is a clear answer to your main question. You definitely cannot get HIV/AIDS or an STD from masturbating. In fact, it is a very safe way of avoiding all the risks that go with having sex. Although you are physically capable of having sex at your age, there is no problem in waiting until you have a wife.

As for your weight loss, you should go to the clinic as soon as possible. Weight loss can be caused by many things, including stress, diet or intestinal worms. There is a very small chance that you have contracted HIV through a blood transfusion or sharing needles or blades, but in Zimbabwe this is very unlikely. Donated blood is all tested, and medical people and traditional healers know that they should always use new needles and blades.

Go to the clinic or doctor soon. Then you can find out the real cause and stop worrying.

Auntie Stella