Bactrim dosage and side effects

I've been taking sodium valproate, but due to the side effects I've been trying to find an alternative and my doctor suggested bactrim/septra.

Valproate is highly effective against borrelia burgdorferi, but the side effects are annoying. In particular its inhibition of histone deacetylase interferes with the opioid tolerance mechanism. This was disrupting my sleep and causing constipation. When I stopped taking it, I had a rebound of REM sleep similar to the effect of naltrexone. I started with a dose of 500 mg per day, then reduced this to 250 mg per day, but I was still having trouble tolerating it.

I was taking valproate, minocycline, and cefdinir. After discontinuing the valproate, the herxing diminished over the next 2 weeks, even while continuing the mino and cefdinir. Valpoate has a very slow elimination, and can take several weeks. I've tried cefdinir on and off. It increases the Lyme herx, but doesn't seem to have any effect on bartonella. Minocycline does kill bartonella, but it seems much less effective without valproate.

I've taken bactrim before and my concern with it is the diuretic effect, which was really bothersome. This is the main reason I went back to valproate. So I tried taking just once a day 400 mg sulfamethoxazole and 80 mg trimethoprim, plus mino and cefdinir. I am getting a surprisingly strong herx from this, both Lyme and bart.

I'm wondering what dose of bactrim people find effective? I don't want to take too much of this because it screws up my sodium and potassium, but I'm surprised such a low dose is effective.