Hello Amanda, an alteration in platelets – low in your case – is not a disease in itself but is the symptom of another underlying condition. In the beginning it should not have any relation to the pain in the knees.
The symptoms that you present in the knee are very general, that is, they can belong to many injuries, but if it calms down when you walk or are at rest, it could be that it is tendinitis.
In the following article we explain how to relieve knee pain naturally: https://salud.uncomo.com/articulo/como-aliviar-el-dolor-de-rodilla-naturalmente-23895.html
But if you continue to notice pain, you should visit a doctor to do the relevant tests.