Pink blood

Becky
Hi all 
So I am 12 weeks 1 day went for my scan 3 days ago everything was al good baby's heart rate fab n baby growing nicely
So we hadn't had sex since finding out 3 weeks pregnant so yesterday decided we would do it.
However tonight I now have had a bit of pink blood phoned up hospital helpline midwife section the lady said not to worry it could be sex that has caused it and to lay down and have some rest and today I must admit my nearly 3 year old has been having really bad tantrums all day and then got out of her car chair while my husband was driving along 😭But it still hasn't put my mind at rest I am a worrier all the time  any way and have been for a scan at 8 weeks 10 weeks n 12. 
Can sex really cause pink blood.
Thanks ladies