ask your other half to go with you, to ask what documents they need. (i use to have all documents copied, x 5 copies and put all of them in a file. so i will have all if they ask.)
go to the nearest immigration to extent another 30 days with tm30, a passport size photo, 1900b, bring a blue pen to fill in 3 forms. contact Sukhumvit Veterinarians soi 51 if needed.
passport, copy of passport (can be done at the shops nearby), a small photo, tm30, 1900 baht. plus a few hours of waiting ? bring a blue pen cos you will need to fill up 3 forms.