Congratulations on having a baby girl. It is nice to know that you have lost a considerable part of the weight you gained during your pregnancy, you must lose the rest of it soon. Overweight is always a problem especially with the problems that you have explained. The symptoms of pain in the knees and feet that you have explained seem to be rather non-specific. It is unlikely to be due to a knee/foot problem. The problem seems to be weak muscles of the leg. I wonder if you do any kind of exercise. Please start some regular exercise now. I know it is difficult with a small baby but you will have to find time for a little exercise. If you want you can take the help of a physiotherapist or a yoga instructor but you need to do something. If you cannot do systematic leg exercises then the next best thing would be to walk at least a few km everyday (any time of the day that is convenient), the walks would automatically exercise most leg muscles. If the problem persists despite regular exercise and despite losing weight, please consult an orthopedic surgeon. At this point this seems unnecessary as the pain is either due to weakness in the muscles or due to fatigue.