sounds like a bad outbreak of cold sores, or herpes simplex.
do you have a hx of cold sores? if it is, it's viral.
since it's so extensive it also sounds like you need an antiviral med like valtrex.

i'd call your dr first thing in the am.
make sure you don't kiss anyone.
don't share any glassware etc and put dishes in the dishwasher.
it's contagious if someone else comes in contact with it.

i'm not positive, so checking with your dr would be important.
could come from stress. it's also possible that it's immune related.
i used to get cold sores a lot and i take valtrex daily. i havn't had any problems since.