What's your medical issue that you would be denied travel by plane? Anyway, go to Laos. The Cambodian and Burmese borders are closed (except for Mae Sai-Tachilek, which is open if you sign up for an expensive tour via a Burmese agency and get your visa through the Burmese embassy in Bangkok or the consulate-general in Chiang Mai).
Land is fine if you own a car...in many ways more exciting than flying, which is a form of public transportation. In any case, definitely stay out several days and return to Thailand using a different border crossing (I almost always do this).
That is very reassuring. Thanks for sharing. What airport? Airline also if I may ask? My understanding is that Air Asia customers arriving into Don Muang are more likely to be questioned than passengers arriving on full service carriers into Suvarnabhumi.
I've tried sending you a PM but either you haven't seen it or it didn't arrive. Anyway, sorry to hear about what you went through. I suspect your length of stay in Cambodia as opposed to frequent entries is what concerned the IO.