Flood has had problems in that area in the past - he spent a large part of 2009 on the sidelines after rupturing his Achilles in his other leg - and revealed he has been playing with this injury since the opening round win over Wales.
But with England chasing their first Six Nations title in eight years, Flood is keeping his fingers crossed he will make the Calcutta Cup head-to-head on March 13.
"Unfortunately it got worse and worse after happening in the opening ten minutes and by half-time it was pretty sore," said Flood.
"It's not bad and we will monitor it - I got a similar sort of thing on Monday and I got some treatment and got it sorted.
"It's an issue of tightening, maybe a bang, I'm not sure. It should be fine, I'm just conscious of it, having ruptured my left Achilles.
"I'd like to think I'll be training sometime this week. It's a shame because it's only a niggle but it may turn into something different."