Not true you have to finish 10 days. You can stop at any time, especially if you're switching to antibiotics.
I don't think epsom salts will help that.. I probably wouldn't bother unless there's no way you can get meds for days for some reason.. in that case it couldn't hurt.. I'd start small if you wanted to do that.. 1/4 tsp per gallon, predissolved like the aq. It must be pure 100% magnesium sulfate with no additives per the ingredients label. You can increase it slowly up to 1 tsp over an hour.. I wouldn't do any more than that. He's not bloated.