Kristina,
Do you eat liver and kidneys? Nothing increases the immune system like
retinol (the active animal based form of vitamin A)(Far more effective than
plant based carotenes), and the vitamin D also helps. People have dropped
their bundle about vitamin A because you can overdose by taking supplements.
True hunter gatherers eat offal. Personally I suspect that it is important
to eat offal if you are eating high meat, low carb diets. You can kill a dog
or cat or lion if you just feed it steak or chicken breast, but they do
nicely on steak, liver and ribs.

Why wouldn't you just try the antibiotics and see how they go?
Tetracyclines have very little toxicity- they are given to people for
decades for moderate acne or to prevent chest infections. Mostly they never
notice any side effects. It does not suppress the immune system, that is an
urban myth (propagated by doctors to discourage over usage of antibiotics).
If there are active bacteria, then only tetracycline will do the job.
Unfortunately the longer you leave it the less effect they have, and the
text books aren't enthused after a long period of infection. But there is
not much other hope.

Ben