Chronic infections usually leads to chronic antibiotic use which usually leads to chronic infections which usually leads to chronic antibiotic use. See the circle.
Also, when an infection is treated, it does not mean all traces have disappeared. Since you can't take antibiotics all the time, nor should you as already pointed out, you'll have to get your body to do the healing.
Natural infection killers include anything that boosts the immune system like Vitamin C, Zinc (don't take more than about 45-50mg's of Zinc a day. Count all sources, food and supplement), Astragalus (don't take if fever is present) and Echinacea (don't take for more than a couple weeks or so, without a couple weeks break if you want to continue again). Oregano Oil, Garlic, and Colloidal Silver are great at killing infections as well.
If I had chronic infections I would avoid sugar, caffeine and alcohol. Do a infection kill using Oregano Oil and Colloidal Silver for a few weeks. Then continue taking Vitamin C and Astragalus as well as a multi-vitamin/mineral (the multi-mineral should give you some zinc, take it separately if you want more) forever. Astragalus could be dropped after several months, but it's good for the immune system so you can alway use a maintenance dose if you want. I don't take Astragalus, but if you've got chronic problems you might as well bring out the big guns and keep bombarding.
Then, and this is probably the most important. I'd replenish my probiotics. Probiotics are beneficial bacteria. They're present in and on your body and responsible for many things such as aiding in digestion, assimilation, immune system and keeping bad bacteria in check. A healthy flora of probiotics is good for all sorts of problems, infections being one of the biggest. The reason this is so important is because all of the antibiotics you've taken have killed all the bacteria in your body, the bad and the good. Without the good, the bad easily come back, hence the reason chronic antibiotic use cause chronic infections. Replenishing them extremely well will not only fight infections, but it will prevent them.
So get a probiotic supplement from your local health store or research and find a good one online. Look for one that is multi-strained, high count, and enteric coated so that it can pass safely through your stomach acids.
There's a specific strain that Mercola (a real doctor that treats his patients naturally) reports to have the highest success rate of survivning and planting itself within you, Lactobacillus Sporongenes or technically called Bacillus coagulans. If you can find one with that, go for it. FOS in the supplement is also good, because it feeds the probiotics.
Take the probiotic in a higher dose for the first couple weeks, then at regular dose for a few months. If you've got chronic problems there really isn't a problem in high dosing for longer than two weeks, so if you really want to get this straight, go for it. After that, you can just maintenance dose indefinitely. Remember to do this after any use of antibiotics or use of infection killers like colloidal silver or oregano oil.
You can also get additional probiotics from yogurt (plain, remember avoid sugar), kefir, or fermented foods like sauerkraut, pickled foods, etc. However, if all you're going to do is go to the grocery store and buy sauerkraut and pickled beets, don't bother. Those foods you find in the grocery store are not "live" with probiotics. They're either just flavored to taste like fermented foods, or they are fermented but then have the probiotics killed through pasteurization. You'd have to find true non-pasteurized fermented foods online.