Yeah I had a pretty similar experience to this. Although in mine my mum didn't see the marks on my arm as there was a curtain between us while i was being examined. The doctor asked what it was and I don't think I said anything, just mumbled until he moved on. I think he wanted me to open up but I couldn't with my mum sitting there. When we left the appointment my mum asked me jokingly "you haven't been self harming have you". She had no idea.... I think she just believed what she wanted to believe. I was so sure I was going to be found out then and was terrified!