Doki's medical expenses

On June 19th I had to take Doki to get his check-up, the initial reason I had booked that appointment was to help him with his itching but there I was informed there was an irregularity with his heart. His vet informed me he had a heart murmur, caused by turbulent blood flow within the heart. There are six levels of severity and from what my vet could tell, Doki is somewhere around the third. While most dogs tend to live nonchalantly despite having these murmurs the problem could develop into something more leading to bigger problems in the long run.

This week I finally got around to calling the Animal Hospital on this issue and the medical fees are something I cant pay or hope for any assistance from my family. I'm a minor and currently in the hiring phase of my first minimum wage job, as much as I would like to work to pay the fees myself it would take me three to four months to pay off. Doki has been showing more evident signs of having trouble breathing as of late and that's the main reason I'm desperate to get him an appointment as soon as possible. The earliest available opening is the 27th of July.

I've had Doki since I was in middle school and as silly as it sounds, he's like a kid to me. Each day he brings me so much joy just by existing and laying there doing nothing but being cute and lovable. Any amount of help is heavily appreciated, even simply sharing this around would be enough for me.