Yes, mtx shots work for years for some people, but very simply it takes months to reach effectiveness, and seeing she has not been dx for very long it seems like she was probably on an RA doseage, rather then a crohn's doseage which is more for me.
In fact it has been the only thing that has worked for me in more then 5 years of being dx. I tried all the oral meds, remi, and humira and they did not work, but this very old drug worked very well for me.