We miraculously managed to get a good deal that we could blow all our savings on to get this new HVAC unit installed about a year ago. In the last few days, it's suddenly started producing a sour smell, particularly in my room. Looking up the issue, all I see is people saying to call someone to get it cleaned because it's mold and/or bacteria build-up. I changed the filter, but the one that was there was barely dirty at all, so I don't think that was much of a fix.
I can't go into detail, but there's a lot going on right now and we can't afford much. We barely even have time to organize fixing something like this. But I don't want to take risks with our health.
Can I get some advice please? What would y'all do?
*also my god the youtube algorithm-fueled thumbnails that come up when searching for tutorials on what to do about this are truly horrendous, look at this shit, just straight up embarrassing

For the sake of keeping my info private, I'll DM ya some pictures I took