There are also other reasons such as:

3- Thrombocytopenia:

When spots appear on your legs, this is a symptom of thrombocytopenia. This occurs when there are low levels of platelets (or white blood cells that help clotting), a reaction to medications, or an immune system disorder, and can also be due to leukemia.

4- Constant tension:

Due to prolonged fatigue, spots may appear on your chest, neck or face. This happens during childbirth or while lifting weights. Other causes of this condition are prolonged crying, vomiting, or excessive coughing.

5- Interactions with medications:

A reaction to certain medications may cause such spots to appear. This is an allergic reaction.