HELP!! MY chickens leg doesnt work???

Hi We have had four chickens for about 6 weeks and bought them when they were point of lay.

Our little redco Tikka sarted to get attacked by our Sussex, Flicker. it started with feather eating but developed into an all out attack leaving little Tikka with her back covered in blood!

we have stopped this using stockholm tar and purple horse spray. Tikka then stopped eating and looked very dispondant. She got very skinny so we have started giving her a mix of mash potato, ground layers pellet, fat balls, chopped veg. she has taken to this and has started to get some meat on her bones.

things looked better for her but then yesterday when we let them all out of the coop, Tikka couldnt walk and kept falling on her face. we have checked her and her left leg is completely lifeless.

On advise from other forums i have checked for any marks, cuts or breaks but cannot find anything.
she has pecked nearly all of the feathers from the top of the leg but gives no painful reaction to pulling, poking or prodding from myself?

i dont know whether i should attempt a splint for support?

she looks far healthier and wants to eat and drink but the leg just seems to be useless.

She doesnt seem to be in pain so the last thing i want to do is put her down but i dont want her to suffer.
i havent got the money for vet bills and dont know what to do for the best?

Please help
Dave