My mother was tested positive for Covid on March 23rd she was is ICU for 10days and 6 dose of remedisivir injection were given to her , She was recovering very well after getting discharged and her Rtpcr came negative on ,9th April ,she was Given Medrol 16md,8mg and 4mg for 21 days with multivitamins but From last 3 days her spo2 falling below 90 and when she is asleep , I don't know how this started suddenly Her Spo2 is maintained when she is awake but it falls suddenly whenever she try to sleep , Please help what should I do next