thanks for the info.

i talked to the administration again and they said i can apply for a one-time, 1 week thing (i'm not sure what to call it because its not an extension of the original visa, i think its a new tourist visa?) for a 1900฿ fee. lucky for me, the new thing should expire on the day i leave. its all still very vague to me, but they are taking me to the immigration office on tuesday morning. if that doesn't work out, i'll have to find a way to get out of the country and come back in...