I probably scooped out the nasties just in time before they could replicate any further as I have a very tasty beer. Lesson learnt, don't leave a beer fermenting for 3 weeks and constantly open the lid to check it out! That's the great thing about beer is the learning (often from your mistakes) from brew to brew.
On a side note I brewed 100L of Lambic last night and not being used to cooling such quantity I gave up and put into fermenters. Split it into 4 fermenters and put in the fridge at zero degrees. So wake up this morning to pitch the yeast and one of the fermenters has already started fermenting. This has happened once before because I left it 2 days before pitching (lesson learnt) and I tipped due to a large amount of DMS.
I fear I may have to do that again but considering that's how they actually make lambic in Belgium, this may have hope?