There isn't a company that specialises in provide insurance cover in Thailand so your best option would be to click on the insurance tab above, select travel insurance, input your trip details and see what products come up. Each of the products will give you a summary of what is covered and access to the policy wording so you can see for yourself what cover is right for you.
The main things that people look for is the cover provided by the medical, cancellation and baggage sections so try to find policies that provide sufficient cover for you in these areas. Then look at the small print to see if there is anything that specifically excludes your circumstances.
Hope this helps, if you have a more specific question about the cover provided I'm sure we can assist you on here.