When is dka dangerous?

Hi all,
Had a rough couple of days actually more like nights. For some reason my pump was getting air bubbles into the reservoir after a couple of hours of setting it up. My blood sugars were going up and down and at first I thought it was just something with me, however Sunday night I woke up at 3 am with burning stomach pain and naseau and with a bg of 400! Did an injection, changes entire pump site and reservoir and by 7am was back to normal and besides being tired from being up was ok. Then again last night awoke at 1 am to extreme stomach pain that I cant explain and nasaeu but no vomiting with a bg of 300, did an injection changed pump and reservoir again drank some water, by 7 am was 200 and by 8:30 am was too low at 60. I know I had some dka as Ive been a diabetic for 26 years, however Im a stubborn one when having to admit Im sick but last night I could of used some help. When is dka truly dangerous, I heard only when theres vomiting, is that true? btw I did contact minimed and some new lot number of supplies are on there way. Also decided to go back on the sensor which I haven't used in a loooooong time, anyone know why when charging the green light flashes then goes to the red flashing light, changed battery, is sensor no good? Thanks!