Hi. Covid stinks. Was your mom tested and came back positive? Have you tested? So many do assume they had or have covid, I will say. There are so many viruses out there and it really is not always covid. In fact, often it is not. So, get mom tested and you tested if you haven't. Because it may be, isolate with your illness to control spreading it. Have you been vaccinated? I have had covid twice, confirmed both times. The first time was pre vaccine and lord have mercy, I was SICK. My whole family had it and I was the sickest. One son barely had a cough and never a fever. Another felt ill for about 2 days. My husband had a fever and was sick for about 5. I was sick for two weeks. I lost my smell and over a year later, it's still not fully returned. The second time we got covid, much much milder. Really, like a cold except I had quite the headache.
Comfort care is the best thing for covid. Fluids, rest, ibuprofen if you can take it. Yes, throat losenges to ease that pain. I drank a lot of tea. I had a little thing you put on your finger that tells you your oxygen level. :>) That was the rage when covid was going around pre vaccine. Your heart racing is likely because of discomfort or anxiety. If it continues or you have chest pain, call your doctor or go to the ER. Same if you have shortness of breath.
Phlegm in the throat causes that thick mucus feeling. Have you ever heard of mucinex? It's something that thins secretions. It can help, but talk to your mom about it.