from what I'm seeing with refusals today at entry points and turmoil at immigration offices, imo, there is some kick back on its way due to the garbage posted all over social media since Friday.
Thailand Visa on Arrival that can be acquired at the time of the arrival to Thailand and lets tourists stay in the country for up to 15 days was recently granted to five new countries. Starting from 14 April 2019, citizens of Georgia, Mexico, Vanuatu, Nauru and Russia will be able to apply for Visa on Arrival at Thai airports and border crossings.
Thailand visa exemption giving the right to visit Thailand visa free for up to 30 days was recently granted to seven new countries. Starting from 14 April 2019, citizens of Latvia, Lithuania, Andorra, San Marino, Ukraine, the Maldives and Mauritius will no longer need to apply for Visa on Arrival but will be given visa free entry to Thailand
For Thailand, the 6 month validity rule was dropped a long time ago (December 2011 if my memory serves me correctly) for most nationalities eligible for visa exemption. Consular web-sites are rarely up to date, your passport needs to be valid only for the period of stay.
If you cannot get an extension in country, you have 2 choices. Apply for a new passport BUT you will continue to be on overstay or fly back to your country of passport and apply there.
No country in the region is going to allow you entry with less than 6 months passport validity apart from maybe the Phillipines as i am certain like Thailand, they recinded the 6 month rule.