mare abortion and lameness

Question
I have a 5yr old Quarter Horse mare that we bred for her first baby last year.  At about 4 months into her pregnancy she became lame and lost a lot of weight.  We kept her in a stall and lasered her feet (which we would have had to put her down if it wasn't for the laser, she was that bad), anyways she aborted the fetus at 167 days and walked fine the next day.  She was out on pasture all last winter and this spring (she was no different than any other horse) then we bred her again in late April.  We have kept her in the barn lot since we bred her so I could keep a close eye on her.  She is 115 days today into her gestation and is going lame and losing weight again.  Have you ever seen this before?  I have raised many foals and have done a lot of research in the last year and  and cannot find anything to do with this.  We did have her checked out at the vet after she aborted last fall and everything checked out fine and he said she was sound to breed.  Could this be a progesterone deficiency?  Please help.  
Thank you,
Christi

Answer
IT COULD BE A PROGESTERONE PROBLEM. HAVE YOU HAD HER CHECKES TO SEE IF THE FOAL IS STILL ALIVE. IT MAY HAVE DIED AND IS BUILDING UP A TOXICITY THAT COULD CAUSE FOUNDER.

THIS WOULD BE MY FIRST STEP, AND IF EVERYTHING IS OK, HAVE THE VET CHECK HER HORMONE LEVELS