irritation, inflammation, and tenderness

I'm on my fourth cycle using the Diva Cup.  For the most part it's been pretty amazing, and a minor adventure in experimentation, but this time around I've developed an irritated and inflammed area on the back of my vaginal wall (where the suction seals the cup.)  It's tender to the touch.

I have a very heavy flow and on my heavy days (2 and 1/2 out of a five - six day period) I need to empty and re-insert the cup as often as every two hours.  I think the frequent creation and breaking of the suction seal is the cause.  Today I'm weaing pads for a while, but I've got an active day and would love to wear the cup again.

I've checked the memories section, but didn't find anything really addressing this.  Anyone out there dealing with this issue?  Any advice is much appreciated.

Yours menstrually  :)