Should I be worried? Spotting at 12 weeks 4 days..

Monday had 12 week scan and everytging was fine! So Wednesday night i had a pulling kind of ache to the left of my abdomen but i do get this now and then...then thursday after lunch i had diarrhoea and then felt fine again. I then later went to the toilet and there was light brown when i wiped...totally panicked and went hospital the dr said it seemed normal and some people even bleed during pregnancy. Its not stained my under wear and this morning when i woke up my discharge is clear again. But I am so so worried. The dr said i can go for an ultrasound today if worried...bit he thinks its totally normal. Anyone else had this? Im worrying now over every twinge 😭