I used to bathe it once a day due to daylight restrictions but twice a day would be more ideal with hi bi scrub. Dry it of with a CLEAN towel or cotton wool and then cover it in iodene or detol, make sure its the wound stuff though and not the floor cleaner detol!! And follow the instructions on the bottle don't be tempted to add more detol as is can irrate their skin if its not diluted down correctly! (or any liquid wound anti baterial I assume would esssentially do the same)
Make sure you get right down to the skin and that you not just covering the fur!
She was rugged as well because I didn't have the facilities then to bring her in so I made sure I wiped the inside of her rug with dettol too.
Ive just recommended a mixture of sulphur and sudrcreme for mud fever which is the same as rain scald. Aparantly works wonders and is really cheap on ebay. You put it on the scabs and by the next day the scabs are loose and falling off. Its cheap too. Got 50g on ebay for a quid and already have sudocreme in the cupboard.
Our vet always said to leave it if mild as most lotions and potions just give it a better environment. If bad, use vets Pink Lotion, bloody incredible stuff.
If rugging really check to make sure they aren't over-rugged and don't rug wet.
Hexocil and pevidene shampoo, scrub then leave it in. I'd try Terramycin foot spray (for sheep) if I had one with it now, seeing how well it has worked on mud fever.