Sad Emo, Kazar and everone, thanks so much for your concern! Here is an update. . .
He's doing better. He made it through the weekend and I brought him to the vet on Monday (his regular vet). He examined him and found that his bladder was empty - which is good - he wasn't blocked again.
He changed his antibiotics (the other vet prescribed antibiotics that don't have a high success rate) and his food (the other vet put him on the wrong cat food formula - one that helps prevent the formulation of crystals - but should have put him on the formula that helps break down and eliminate any remaining crystals or sedement), and put him on prednisone.
Within a day of these changes, he stopped going to the liter box so frequently and the volume (output) increased. He's done with the antibiotics now, and I'm weaning him off the prednisone. The doctor said that once he's off the prenisone, his output should increase even more.
I'm keeping a close watch on him . . . but I'm starting to feel like he may make a full recovery from this.
- CF
PS: He and his sister are getting along again. It took about 4/5 full days for her to finally accept him again. Now they are sleeping together and cleaning each other again . . . whew!