I had a similar incident this weekend, incidentally an U18's match, the attacker had rode two foul challenges and stayed on his feet ,but he was travelling at speed with the ball slightly running away from him.
He was heading straight towards me and I couldn't see what was developing behind me and my fear was either another defender took him out or he might dive in on someone in an attempt to get the ball.back.......I blew for the foul on him just as he played an inch perfect ball to a teammate ....... que the moaning and outrage and me having to apologise.
My thought process was following a seminar run by a Premier League Ref who showed clips were refs had played avantage after a couple of challenges on attackers which resulted in things going badly wrong .......in one a defender suffered a broken leg with the attacker diving in, another attacker issued a red after again diving in and the third in a mass confrontation when the third defender cleaned the attacker out.
Having seen the aforementioned incidents I tend to err on the side of caution and go with a foul especially after a second 'nibble' unless there is a clear run.
On a side note.....I've had a manager tell me before a match that his team didn't want any ' advantages'......turns out he had two centre halves who he wanted in the opposition box at every opportunity .......is he okay to request this?