There's quite a bit of misguided information in this topic, along with some fairly good advice. The challenge left to the reader is to discern which is which. As far as I know, no doctors have posted. Nor am I a doctor, but many of my closest/immediate family members are doctors: I grew up with them, and have a degree in biology.
Knowledge increases continually, and what is called "fact" today may be classed as "myth" tomorrow. That said, it is my understanding that there are some credible reasons to discredit the popular notion that bacteria will evolve resistance due to misuse of antibiotics. Nor are there many types of antibiotics because there are many types of bacteria, with each antibiotic targeting a different bacterium. Before the discovery of special categories, such as nanobacteria, there were predominately two types of bacteria, and virtually all antibiotics would be best used against one or the other of these: the grams-positive and grams-negative bacteria, so named on account of their staining properties. In general, the penicillin variety of antibiotics will best attack a grams-positive bacterium, with the exception of a few grams-negative bacterial varieties that also are susceptible to it. A "broad-spectrum" antibiotic, such as amoxicillin, is so named due to its ability to prevail against a wider range of grams-negative species.
The "strength" of an antibiotic has much to do with the dosage in which it is taken. Doctors have been trending toward higher and higher dosages, perhaps as more resistant bacteria become more common, or perhaps this compensates for weakened immune systems.
Augmentin (amoxicillin + clavulanic acid) is preferred by many doctors nowadays for more stubborn infections. The clavulanic acid apparently increases the effectiveness of the amoxicillin, prepping the ground, so to speak, for the antibiotic to penetrate and do its work. While a typical course of antibiotics might be five-seven days, an infection of, say, the inner ear, might require treatment for 10-14 days.
My first thought, in answer to the thread question, was "Augmentin." I see that I am not alone in this, as multiple others have also suggested this. In Thailand, this will probably come in the form of 900 mg. amoxicillin + 100 mg. of clavulanic acid. In America, the ratio might be 875/125 mg. It is possible, by purchasing lower-dose pills of a couple of ratios and then taking more of them, to compensate and approximate the higher clavulanic acid ratio (I have done this). But it may not be a significant difference, and the over-the-counter formula will probably work just fine.
Be aware that antibiotics, particularly a broad-spectrum antibiotic, will work against all the bacteria in one's system, including the good ones in the gut. The doctors in my family growing up recommended having some yogurt to help replace some of these once the antibiotics course had finished. Even then, this is likely to alter the natural balance, and, where possible, antibiotics should be avoided. Take them when necessary, but they should not be one's first option.