You go to the Ministry of Labor where you got the Wrk Permit, show them you stop working on 15th Feb and cancel the work permit on that date. Go back to Immigration with the letter from the Minsitry of Labor and all other documents to cancel your current Extension of Stay and apply directly for a new Extension of Stay.
The tourist Visa give you 60 days on entry and an extra 30 days if you apply for an Extension of Stay. If 6 Feb is your last day and your plan was to stay until Jun this year, this tourist visa is not enough.
You might get another 60 days based on unable to travel, but a short holiday abroad to apply for a new visa is most likely the only option.
Thanks for uploading the Pattaya version of the requirements for the Extension of Stay based on being over 50 years of age. Good luck with the application and always prepared to answer any question.
7. You can apply for an Extension of Stay during the last 45 days of your current stay. You will not loose days by going early as the extension is added on your current stay.
Do not wait until the last day to avoid problems if you might not have all documents correctly.