İf over 90 day you can't clear up my friend you better go out Couse if they find you outside they will make big big problem for you and you have to pay more then 100.000 but if you go airport and pay 20.000 it will be no problem if you flight on same day. ( But if you change your passport and your name you can come again ) bit long story brother
Don't do panic just to to airport with a flight ticket to your country or some where outside of Thailand you will be fined 20.000 baht not more and if you pay that money no problem but you will get stamp for do not enter to Thailand again for long time that's all
Take train from hua lumpong station to Cambodia border only 50 or 75 baht but not 100 baht and come back 3 day later very cheap price you will get visa
I been in pp and do not be there as you say party beer or classic reasons as you and was pp boring it is my opinion :) if you like siem reap just stay there good time