If it is truly Vasculitis it can be a serious condition and is not cured by showers or baths of any sort. You need to find the right doctor to diagnose the cause of the vasculitis. If you have hep c this may be an indication that you have cryoglobulinemia. Typically the vasculitis outbreaks come and go but this does not mean the underlying disease if there is one is gone. to confirm vasculitis a biopsy would need to be performed of one of the purple areas wich is a simple outpatient procedure and can often be done by a dermatologist.
Do you have a very qualified hepatologist? The test for cryoglobulinmeia has to be done at a lab that has the proper equipment and understands how to perform the test. Many labs will do the test but they don't perform the procedure correctly and there can often be false negatives.
Typically a teaching hospital lab will be prepared for this. They use special test tubes that are warmed to a specific temperature when they take your blood which must be either stored at that temperature before it is spun, or the process must immediately begin. The blood is seperated and cooled to different temperatures over the course of several days to see if cryoglobulins form and what percentage there are in your blood.
Vasculitis it seems can be cured by taking cold showers or baths. It seems that this improves blood circulation. A regular swim at the beach or in a cold water pool will help.