Six wks pregnant having pain in lower abdominal

Patient: Hi doctor,i am 6 weeks pregnant, this will be my second baby, my first delivery was normal. last week i had some paid in my lower abdominal, i also had slight bleeding and brown discharge as well. i also visited the doctor. she did Ultra sound and some blood test. the ultra sound reports says :. Uterus is seen gravid with single viable foetus with regular cardiac pulsations.. CRL= 0.8 cm corresponding to 6 weeks +6 weeks…… +=6 days.. EDD according to fetal measures is 26/3/2016 …..+-6 days. Average cervical canal length and internal os caliber at the time of examination.I have read certain articles of Ectopic pregnancy, i am scared if my symptoms are leading to this problem, can you please help. Thanks