Is what your pharmasist recommedned Canesten with hydrocortisone? If so, I'm not much help as the symptoms you describe are exactly what I suffered from for years before finally finding this as my 'cure'. If, however, you have Canesten without hydrocortisone then it may not be working for you, as it didn't for me. Whether or not, in any event, you can use Hydrocortisone of this strength on your children though, will need to be checked out.
Hope this helps.