When I go to stand up after picking something up or picking up my baby, both my legs feel like jelly and have the feeling like my legs are about to collapse beneath me and have to sit down right away. This feeling lasts about 5 to 10 mins and happens quite often in the day as I m having to pick up my baby (newborn) for any needs for her and when I m tidying up a bit. This started without cause and am going on day three with this. I haven t been picking up anything that weighs no more then 20 pounds maybe. I am 6 weeks post partum with a natural delivery. I m 25 and weigh maybe 130 pounds and 5 4.