Hi Im dr hema physiotherapist As a routine I need few information from my side 1.type of pain, unilateral or bilateral, 2.z the pain z gradual or sudden 3.any other illness 4any swelling or sounds in the joint. If the pain is sudden onset it may be due to sprain If gradual there must be strain yo your joint due to prolong standing, or due to gradual increase in weight after pregnancy, or decrease in calcium that is your body demands more calcium(breast feeding). However, direct assessments helps to find out exact cause. Mean while in home u can try 1.hot and cold packs to ur knee, 2.rest 3.calcium and vit d rich foods (milk products, peanuts, pumpkin) 4.regular exercises, walking, try post natal exercises. If pain persists or more consult your dr or physical therapist for pain killers and modalities which gives u relief. In doubt do reply. Take care