Some of it could be relaxin working on your body. If you feel you can take supplements. Get on a good prenatal, iron and cal/mag. Make sure you take your iron(ferrocel iron is non constipating) and calcium at different times since calcium makes iron absorption more difficult. You need to take the cal/mag twice a day and get 1000-1200 mg a day. Hope that helps. This pregnancy has been particularly hard on my body so far as well. My teeth started to demineralize even, so I upped my cal/mag from the 500mg I was taking to 1000 mg and now they are going back to normal.
Happily married Christian SAHM of 2 boys, DD1 , and DD2 July 2013