To me it sounds like a reaction to those medications. After being pregnant it is possible she did not exercise much in the past few months. I suggest some simple back exerercise on the floor (carpeted) such as half sit-ups and leg lifts. Do every day for a few weeks. Also, her vitamin D3 level is too low. It should be between 30 and 80. I suggest D3 supplements at 1000 to 2000 I.U. a day. Then get re-tested. Most people do not get enough D3, especially in the cold months. Best of luck.