If, when you re-entered the country, you were already on an Extension of Stay (not on a Non-O Visa which is 90 days) then your next 90 day report is counted from your date of re-entry. If you were on a Non-O 90 day stamp when you r-entered then your first 90 day report will be 90 days from your extension date.
You get the Non-OA online via the Thai Embassy in the country where you reside so you must be "home" to apply. Check the Embassy website for their specific requirements.