Stress.
When i get stressed, my levels get completely whacked.
I forget to eat, only have half a sandwhich etc, especially if i'm under pressure and busy.
If you are self employed make lunch a priority. Set apart at least 20 mins, unplug phone etc and have a good meal and a rest. Anyone who rings won't mind being spoken to 20 mins later, (oh, sorry, was on the telephone), and it'll make everything a lot easier.
It won't cure it, but i think it'll make it better.
Speak to your doctor as well, if your lifestyle has changed then your medication needs have too.
It may be that a pump is more convenient and better for you, but i wouldn't advise that unless you have an idea of why you're going so low.
Good luck,