Bunny scratch or biting

Vet tech only pls - I'm grooming my bunny she is old bunny not sure exactly her age but i noticed this in one of her legs and i don't have money to bring her to an emergency vet right now could any vet here tell me what this could be and how to treat it at home if possible? It has bald spots on that one leg and like a scratch not sure if she's scratching her self or biting herself , why would she be doing this? She likes staying to herself i don't pick her up a lot cuz she doesn't like that too much that's why I just now noticed , i groom her like twice a week

Hello - it's hard to say what's going on here.  Possibilities range widely from pain (an area hurts, so the pet responds by overgrooming), to mites, infection (eg a cut that has become infected), to urine scald, where urine trickles down the skin, either as a consequence of the way they sit (arthritis) or bladder or kidney problems (eg overproduction of urine) which can be easily missed in the rabbit.  Rabbits do not show obvious signs of pain and so it is easy to assume that painful conditions are not painful.  It would be a good idea to show this problem to a vet with good experience with rabbits.