all your sypmtoms are ec... if skin is building, peeling and turning white in the shower it really only leads to one road..
ec is uncommon and it seems many derms are either unaware of it, or waste your time with nonsensical diagnosis like impetigo or contact dermitis because they are more common... i suggest you either shop around for a derm who understands and has treated the condition, or look up some of the more successful derm treament protocals on this forum yourself, and tell the derm you have already been diagnosed with ec (this will save you a lot of hassle), and then push for the treatment protocal of your choosing.