I Stopped Using Symbicort And Breathing Is Easier Why Is

i stopped using symbicort and breathing is easier why is this/ I have been using it for about 6 years. With it I can get my o2 levels up to 96% with out it I am at 98-99%. When I do excersise it drops to 92 but recover within a minute or two with out using the inhaler. With the inhaler it takes 4-7 minutes to get back to 95-96%.
Thank you.
Jim
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