SOMETHINGS WRONG WITH MY CAT!?

i have two cats, and they were both pregnant but the smallest one had her babies on the 28th of april 2009 and the other cat didnt bother even looking at the babies... but for the last half hour, she has been miaowing like hell really loud and a lot! and walking funny on her back legs almost like a front moonwalk, and now she's gone and got in the box with her sister and her sisters babies and is snuggling up to her sister like shes almost crying and i dont know what to do?!! please help !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!… i hope she isnt dying or anything