DD throwing up from straining to go poo??

So for about two weeks now DD has been throwing up randomly.  We have been noticing a pattern lately because we've been paying more attention to her to try to figure out what is causing her to vomit.  The last few times I have seen her throw up she is grunting and making her "poopy face"....The dr says she doesn't think she's the reason she is throwing up as to do with her straining but I really think it does.  On the drs orders we cut all dairy and formula from her diet last week and replaced her feedings with ricedream and juice while she has been taking florastore (a probiotic) to rebalance the good bacteria in her belly in case she had a slight bug.  Well we finished the florastore last night and had 5 straight days with no throwing up.  Then this morning we got her up and she drank about 4 oz of ricedream climbed down off our bed and went in the corner and started making all kinds of noise and faces trying to poop.  She stopped for no more than a few seconds and threw up all over the carpet. 

 Has anyone else been through this?  She goes poop 1-3 times a day.  Over the last 2 weeks she has thrown up at least a dozen times and will act totally fine right afterward.  We are giving her pear, apple and prune juice-all that should help soften her poo to make it easier to go. 

I just don't know what to do for her because I can't really predict when it's going to happen.  Sometimes she even does it at nap time.  It won't bother her either.  I'll go in her room and she and her crib will be coverd in throw up. 

 The dr said when it gets to the point that it hurts her too badly to go to the bathroom that her little brain will decide to just hold it in.  She said that is a worse problem to try to fix so to try to make it easier for her to go.  The thing is I am doing everything I know.  Nothing had changed in her diet to bring this on.  She eats some people food, organic baby food and Enfamil formula until we put her on the Ricedream.  Any suggestions??