self-injurious scratching

Question
QUESTION: Hi, my pet rat Chloe is about 7 months old. In January,  I took her to the vet in January when I noticed scabs on her neck and back from scratching. The vet said it was probably mites and gave her a shot and liquid Baytril for a 7 day 2x day treatment. She improved. Then she got bad again and I took her back to the vet a few weeks ago. She got the same treatment-shot and antibiotics. The vet said to come back in a few weeks for a second shot. I'm concerned b/c Chloe still keeps itching herself and has made little bald spots on her back and shoulders from doing so that have small red spots/scabs. I recently took apart her cage and bleached it all and have bought her a new hammock and house. She also had her back toenails cut at the vet. What else can I do to help her stop itching and help her heal her sores? I can't afford to keep bringing her to the vet - I'm a poor college student! I really don't want to let Chloe just keep getting worse but I can't financially keep this up! What can I do?
ANSWER: Is she still itching even after she got better? Aside from the vet treatment, I'm not really sure what to suggest... I treat my rats with Ivermectin, a horse de-wormer (you can probably find it at your local feed store), every 12 days when they have an outbreak, but you have to be EXTREMELY careful because its so easy to overdose them. If you choose to try this, the recommended does is the size of an uncooked grain of rice (or less to be on the safe side) orally.

---------- FOLLOW-UP ----------

QUESTION: Yes, she has always scratched, even in the interim between the 2 cases of scabs and hair loss. Is this normal behavior for rats to ALWAYS be in this itching cycle? Will I forever be re-treating this?
I will ask my vet about Ivermectin - do you know if you I put this in a small piece of bread for her to eat b/c that was the only way she would take her antibiotics?
Thanks.

Answer
No, its not normal for a rat to always be itching... Unfortunately, I can't think of any other alternative other than what you've been told by the vet. If there's no bugs, it might be dry skin... You can put some vegetable oil on a piece of bread for this. You can try putting Ivermectin on bread, but I've found that, while my rats hate antibiotics too, they find Ivermectin pretty tasty.