Sick bird using feeder

I've only noticed a few days ago a very odd looking great tit using the feeder. I did not see it again and decided to wait to take a better look, because despite his odd look, he was very active. 

Today I have had a much better look, and an entire side of his face - eye, cheek, beak area-  has something like big warty growths affecting one side of his face, and his feathers are very messed up and scruffy. HIs overall look is unhealthy, unlike all the other birds. But he is still very active. And he is feeding with all the other birds. There is nothing I can do for him right?

I know I need to take down all feeders and dump the food, am I correct? How long do I stop for? And I suspect this affects the ground feeding table which I guess he has access to too?

This is going to be so hard. And it's so cold at the moment for them.