My doctor wants to get my platelets checked because i've started getting unexplained bruising all over, fatigue and joint pain. what could it be?

Need other testing: Platelets are essential components of the blood that helps control bleeding. When levels are too low (thrombocytopenia), spontaneous bleeding and bruising can occur. While there are several potential causes, autoimmune, viral, malignancy, medication, mechanical, infectious, you will need additional testing if you are found to have low platelet counts. Meanwhile, refrain from physical activities