Need funds for a vet trip

My fourteen year old kitty lost a lot of weight last year and was incredibly itchy. She was given Prednisonol and recovered. Now, she has lost hair again and lost weight and is lethargic. She's still eating and drinking but she won't leave my room. She has cat acne like bumps from chin to tail. I gave her what was left of her unexpired Prednisonol but that ran out today. She started responding to it but I think more is going on. I use flea meds, my other cat is fine and no sign of fleas on my kids. Someone told me she might need blood work to rule out cancer. I think it's dermatitis though, however, between the visit and blood work and treatment, it could run me a few hundred plus. I'm a single mom and just opened my own business last week and that is not bringing in enough to support us yet and have any extra. Anything helps. I love her so much but have no resources right now. Thank you all!