OP said there's a definate lump,,, sounds like more than just molting, though she may be doing that too.
Welcome to BYC Vugaris! Glad you joined and that you posted... sorry your hen is having problems.
When you go to take another pic, see if your friend can help you gently spread her feathers there so we can see what the skin looks like too.
It does seem to be in the area of her oil gland, it may help us tell more if we can see what's beneath her feathers.
Are you keeping her in a dog crate or someplace sheltered for now? Make sure she has some nice fresh water and some food. What are you feeding her?
Welcome to the wonderful world of chickens!