Fluctuating Spo2 level. Is it true?

I was detected Covid positive on 21st April and on 24th April was admitted to Ayushman hospital Dwarka because Spo2 level started to deteriorate and went till 75. Consequently, was on oxygen support in Covid ward. On 8th May,  Covid report came Negative On 9th May, was shifted to Non Covid room. Now what is happening is I am taking minimal oxygen support, but at rest oxygen level is 90-94. But whenever I move for basic things, the level fluctuates and then restores to normal level. Today the Spo2 level dropped to 62 and then returned to 90 within a minute. So I need to know, for a Covid recovered person, is it normal if his Spo2 level goes to around 60 and then comes back normal naturally??* What kind of oxygen therapy should be used at  home?? Doctors who treated there said that there is mild infection left in the lungs, which will eventually go over a period of 2 months. Is it true?? Kindly Suggest!!