Please help with Jays veterinary care

Recused Jay almost 3 weeks ago. His prior owner definitely didn’t disclose any health issues. Jay has had continuous bouts of coughing and breathing distress. He needs a lot of diagnostic tests which I’m not able to afford at the moment being I’m a single mom financially and it’s been a rough couple years. This was unforeseen and I just want the best for him and the life he was never given. My son and I absolutely love him and spoil him with love. His pet insurance won’t kick in until December and even that would be considered pre existing. His owner told me he was 2 years old and after being promised his records I never received I was able to receive them from Banfield based off his rabies tags. He’s only been to the vet twice in his life and he isn’t actually 5 years old. Idk why she had to lie about that. He has buildup on his teeth. I also took him to the vet over a week ago and he was put on antibiotics for kennel cough. It didn’t seem to clear up so I took him to ER when he was in distress one morning and they suspect something with his heart or a collapsed trachea. I couldn’t get a definite answer because the testing was so expensive and I’m struggling as it is. So I’m reaching out in hopes of getting donations for his care. He’s not even fixed. It’s just ridiculous that he wasn’t taken care of. He had so much anxiety when I got him and he’s finally settled in. We’re almost at our goal for testing and getting fixed so anything will help. Even sharing his story. Even then I know he’s going to need continues treatments especially because of his trachea. The poor thing can’t even drink water without choking. Thank you all for hearing me out. I appreciate it so much.