Can I Extend My 60-Day Tourist Visa in Thailand for Another 30 Days?

Hello

I'm sorry to bother you with my question.

I have been living in Thailand for over 10 years on a work permit. I recently stopped working at the school I was working at and got a 60 day tourist visa. I still have a little over a month on my 60 day visa. My question is can I still go to immigration at Chang Wattana and get another 30 days. I'm on a USA passport.

I have not left Thailand for 10 years do I still need the Medical Certificate? Is there anything else I might need in addition to the normal stuff.

Thank you for your help ....