I had a real problem with recurring blocked ducts, in particular my right side. There was nothing I could seem to find that was causing it except it did seem to happen when I was particularly tired. I tried hot showers, expressing, massage, proper fitting maternity bras, frequent feeding from that side and went to the family centre to check he was latching properly and slowly it has happened less and less often and touch wood I haven't had one for more than a month I think. Sorry I don't have anything more useful to say, just wanted to let you know you're not alone and that hopefully time will settle things down for you like they did for me. It's tough though, it really made me depressed and I wasn't enjoying b/fing at all when it was happening all the time.
Best of luck