You can also experience trauma without experiencing PTSD.

I can't think of anything worse than worrying about a sick child, so trauma is there, but the reaction to it is sounds more like prolonged and extreme stress.

It's rare to experience PTSD without experiencing flashbacks or re-living the source of trauma. It's that mental dissociation that's the real definition of PTSD. It's like switching off your 'now', and being instantly zapped into literally reliving that moment, quite often it will feel completely real.