L.L.
I am Rh negative. I had a healthy boy, and then a miscarriage, which was harder emotionally than I ever could have imagined. I'm so sorry. At the time I was convinced my miscarriage was due to a stomach virus that a friend had given me. It's completely natural to want to blame someone, but as everyone else has said, miscarriages are very common (20% of pregnancies). We waited three months, didn't conceive the first cycle, and then did. I have an amazing second son, who is the most positive, resilient child you could imagine. Such a blessing. I still grieve my middle one.
Rh factor and lack of shot couldn't have caused a miscarriage so early. I understand your need for a reason, but it's really impossible to know. Sending you thoughts of peace as you make it through the next several months....