I'm having trouble breathing properly; I can only breathe through my mouth, especially when I'm lying down. I've done a COVID antigen test, and it was negative, but I'm still waiting on the RT-PCR results. The only symptoms I'm dealing with are leg pain and this breathing issue. My oximeter readings have been quite unstable, usually above 92 or 93, but sometimes dropping fastfrom 100 to 92. This morning, the reading on my left thumb was as low as 89 or 90, while other fingers showed 92 or 93. I don't have any other COVID symptoms, so I'm really worried about what's going on. Could you please tell me what I should do?