4 weeks along is not long enough to show the baby, it is only a cell/zygote at 4 wks along. At 8/9 wks, you should be able to see the amniotic sac and a tiny baby and short umbilical cord attached to the placenta in the sac. Mine was the size of a walnut (the sac, placenta, umbilical cord and the shape of a tiny baby). I have had 5 children and 3 miscarriages and pregnancy cramps are similar to period cramps, but with no bleeding. Some women bleed a bit at times during their pregnancies, mostly early on, usually it is nothing bad, but see the doctor to cofirm it. My first 3 months were so painfully crampy that it scared me, 1st pregnancies are the worst b/c your uterus has never stretched for a baby before. Best wishes for a healthy pregnancy!