I had this problem (it's commonly referred to as secondary infertility). My children are 6 years apart; I had difficulty getting and staying pregnant the second time around. I had no idea that it was possible to have fertility issues after getting pregnant so easily the first time. One of the pieces of advice given in this situation is to not wait the typical year to ask a doctor for help but only 6 months. I also read a great book called "Taking Charge of Your Fertility". It was kind of my bible for a while.
