Hi - I have in fact been in a similar situation where I missed doses for a few days in a row and started to notice some instability with moods, as well as headache and trouble sleeping - that was just after about 2 days or so.

The one thing you need to be really aware of though, and your pdoc should know this, is that if you go without Lamictal for an extended period of time, you will need to begin all over again starting with a small dose and slowly work your way up to your therapeutic dose. The risk of the rash and other side effects is there again if the drug has been out of your system for long enough - I'm just not sure how long that period would be before you have that risk. Good luck - try to get your script soon and call your pdoc to make sure you can start up taking it again at the same dose. Hope this helps.