If you, as a DM, have already chosen to use stunning monsters in back-to-back combats, then in my opinion you've already made your mistake.
Stuns are ok in moderation, but overused (which is a pretty low threshold: I think that stunning a given character for 2 rounds in the average fight is probably too much) they're just fun suckers. Note: I don't consider a single save-ends stun to be breaking this rule - a party has plenty of ways to remove save-ends effects, even if none of them are leaders, so it adds tension. Multiple save-ends stuns however is definately a violation.
If the best tactic for your monsters is to overuse stun, then rebuild the encounter so it's going to be fun.
Being KOed is different. As others have pointed out, it was terrible tactics on your party's behalf to wake you up immediately before the monsters go, and mind-blowingly bad tactics to do it twice in a row.
In fact, if I were you, I would have refused to accept the heal.