Do you mean gall bladder infection
when you say cystitis? if yes then your symptoms are quite easy to explain. Cystitis will block the gall bladder duct. This will cause the liver
to not excrete enough bilirubin
. The increased bilirubin will cause itching to all the skin all over the body. What you need is if you are not cured is to get the gall bladder removed. After that, you will be cured almost completely.
I hope this helps.