If there is any doubt about it, I would strongly recommend going to a proper professional Pest Control company, and quickly.
I've had a problem with termites before in a house in Phuket and they get all over the place before you know you've got them. They come from nests or mounds in the ground usually under your house, but travel up through cracks in the concrete, electrical conduits, wooden frames etc and will eat anything wood, usually wooden door and window frames, or the paper lining on plaster board ceilings (gypsum), or wooden furniture.
A professional company will saturate spray under the house if they can get at it. If not they will drill through the floors and inject/spray. They will also spray around the house and the base of external walls, and puff a special insecticide powder into affected woodwork, cracks in wood, skirting boards and the like. They will return usually at monthly intervals and if necessary repeat the spraying process.
What is important is to get to the source/nest of the termites which is usually under your house. I initially didn't appreciate this and bought a locally available can of spray and sprayed the affected areas around the door frame, but that just drives them elsewhere. And I hadn't realised that they had already gone up inside the plastic electric conduits, had then spread out and were munching through the ceiling board in several different places.
You can often spot their narrow soil coloured trails around and under the house or up the outside and into cracks, -like dried soil about 2 or 3cms wide.
I strongly recommend you get in a professional company. It costs about 6k baht, depending on size of your house, and provides repeat visits and cover for a full year. I think this is a situation where a stitch in time really does save nine!!
