Sounds like you made the right choice.
Way it was explained to me by a vet, is that a cow with acidosis will, as time goes on (in hours) past initial grain consumption, have such an acidic rumen concentration that first all the "good" bacteria die, and then if it continues, all the "bad" bacteria die. The blood pH drops and internal organs (may?) shut down. He did comment that, if they're still alive, they go UP - back to alkaline. And at that point, you have to bring the rumen back to acidic and give probiotic. So depending on where they are on the time line depends on how you treat them.
If you can catch them immediately after consumption, which of course would be ideal, you'd use mineral oil and sodium bicarbonate (baking soda). If more time has passed and the good bacteria have died off, but not the bad bacteria, you'd want to treat with an oral antibiotic as well as sodium bicarbonate. The antibiotic (suggested spectinomycin aka Spectam) takes about 6 hours to really do anything; in the meantime you're trying to restore proper rumen pH with the bicarb. No sense in putting probiotic in until proper rumen pH is restored, as the extremely acidic environment kills off the bacteria.
Now if you're at the point of the cow coming back up - to alkaline - and to alkalosis, then you'd bring them back down to acidic with something like vinegar. Suggested apple cider vinegar.
So you make a guess as to where the cow is at on that timeline, mess around with the pH of the rumen, and try to get the right level.
Sodium bicarb also comes in an injectable 8.4% IV solution and that would be a faster way of correcting the low pH levels, so long as a person didn't give too much and bump them over to alkalosis.
Activated charcoal absorbs toxins in the gut, and I wouldn't be too surprised if clay does as well. Perhaps that bull knows what he needs? LOL. I'm going to guess the "pink stuff" is Kaolin Pectin? That has a similar action to activated charcoal; binding with toxins.
I'd guess that you made the right choice - even if inadvertently - with antibiotics and sodium bicarb and electrolytes - and he sounds like he's on his way back to normal.