Ferdinand has also been criticised in some quarters after it emerged he was flying to Doha to appear as a pundit for Al Jazeera Sport television for the San Marino match.
He said on Al Jazeera Sport: "I met the boss in London and we spoke about my regime and (I'm doing) what I've done at the last few international breaks - the same.
"I was pencilled in to have certain treatments, had them and then I've come away to have some rest time and to recuperate and get myself ready.
"I think obviously the situation with myself and the national team is well documented.
"But this isn't something that I'm doing differently. This is something I've done in past international get-togethers when I've not been involved.
"I've had a course of treatment that I've had to have and then to go and rest and get ready and recuperate - and that's what I've continued to do."
Ferdinand added he cleared the trip with United before flying out.
"I spoke to the club and the club doctors and the physios who have helped me organise the regime that I'm on. But ultimately it was spelled out for us anyway," he said.