I Have Asthma And I Am Over Weight At 255

I have asthma and I am over weight at 255 and 5 8 in height but I'm heavy build,now I have anxiety and some trouble getting a deep breath,I have had 10 ekgs in the last year blood work couple years ago a stress test and they say my heart is fine,now I do get some chest pains nothing that hurts but scares me,and my oxygen flucttuates from 92 to 98 but stays mostly at or just above 95 why such fluctuations.