Get Your Cat Care Questions Answered By Cat Vets ASAP
I am sorry to hear that your boy isn't well. If he hasn't had any vomiting and is still eating then no treatment is required. The clorox tabs would have been diluted with toilet water so hopefully no damage has been done.
The most common problem with ingesting clorox (and many other common household cleaners) are chemical burns to the mouth, tongue and sometimes even the esophagus. Symptoms to look out for is drooling, pawing at the mouth, vomiting, not eating etc. If you do notice any symptoms do take your boy to the Vet as soon as you can as he may require antibiotics and antiinflammatories.
Drinking the toilet water with clorox in it would not account for weight loss (unless your boy has burns to his mouth and is not eating as a result) or any signs of confusion.
At his age there are many conditions that can potentially cause these symptoms such as kidney disease, diabetes and hyperthyroidim to name a few. The way to diagnose any of these is a routine blood and urine panel carried out at your Vets.
I hope this helps, please let me know if you need further info.