I'm not a doctor but those symptoms don't sound anything at all like GERD. If you had it, you'd be experiencing heartburn and other digestive problems which are often solved by not going to bed for awhile or lying down after eating. It sounds like a migraine condition except for the fact it's sticking around that long, but it could be what are called cluster headaches or something like that. The breathing difficulties could indicate covid or anxiety or any number of things but again doesn't sound like GERD. The mold problem could create any number of allergy problems if you are indeed sensitive to it, and if you are able to go to the hospital I'm not sure I understand why you can't stay at a friend's house or with family or motel to get it tended to as you apparently do go out when you have to. I'm also not sure why you'd have to leave, as what they do is scrub it with bleach and then paint it but of course no matter what you do it will come back if you don't have extremely great ventilation in that bathroom which almost nobody has who isn't extremely wealthy or else you clean it regularly once you get it painted. The workers won't be there at night and I assume you don't spend most of your time in the bathroom, so if it is a problem you can get it fixed even with agoraphobia. I know how hard this is, I have agoraphobia as well, so I get that you don't want to hassle with it but it is something you can get done if you need to. The main issue is, though, I don't think you have an accurate diagnosis as of yet. Peace.