I've never heard of borax being toxic (used for a bath or otherwise external) - of course ingesting it is different.
H202 is usually energizing in a bath, because of the extra oxygen.
But ES in a bath (particularly to someone whose electrolytes are as easily thrown out of balance as yours)...yes indeedy!
Symptoms of too much magnesium include muscle weakness, lowered blood pressure (so dizziness would be possible), drowsiness, slower heart rate, confusion, slow reflexes, etc.
I don't know why they added the ES to the borax/h202 bath - I'd definitely leave it out if I were you (because I see no reason why it should be used for scabies).
Also, how many 5-day Kidney cleanses have you done? The kidneys are major players with electrolyte imbalances and we know they were implicated in the ileocecal valve issues...so you're kidneys could use all the support they can get. Of course, the adrenals sit atop the kidneys, so the if the kidneys are stressed, so are the adrenals.
Speaking of adrenals (now I'm being a momma-hen :) last time I posted, I recommended --and always have-- that you definitely take Ashwagandha, but when you responded I don't remember you saying anything about it. Whassup with the Ashwagandha? There's nothing that's more effective, and it's SO beneficial for so many other things (especially the immune system).
'Any relief from the itching yet?