Cat in Storm Drain :(

My sweet baby jumped into a storm drain. He is an outdoor cat that I’ve been taking care of for a year. He recently got very sick and we’ve been trying to get him to the vet for 2 weeks. He lost so much weight suddenly and started to stumble, limping, eye problems, etc. he was looking very rough. Tried to get rescuers to help trap him but had no luck. This morning, we were finally able to grab him and put him in a cage, never been happier. 10 seconds later he busts out (still have no fucking clue how) and jumps straight into storm drain right by my house. Public works took 3 hrs to come, they looked through all the nearby drain lines and could not find him. He is so sick so I don’t know how he could’ve gotten that far, but I’m also worried that he wouldn’t be able to jump back out. Idk. Cats are very strong. He could have gotten out through another opening. I just want him to be okay. I put food in the drain where he was last seen and a plank that he could climb up. Idk what else to do. Any advice?

(This is in Montrose close to Castle Ct)