Looking for suggestions or what have you from those who have cured this. Lately, I have been getting that afternoon crash. I just want to take a nap!

Heres the break down.:I feel alot better when I walk on my lunch break but that usually takes up my whole break when I do that. I've increased my h2o intake decreased my soda. I'm not sleeping well at night. I work 36 hrs a week at the clinic then do scouts with my son and take the kids on a walk the other days. I'm so frusterated! I am trying to do enough stuff so I will be tired and then sleep well, but grrrr. it's not working the way (my) logic says it should. (I also have 2 other jobs that I do on call) last week I about worked my self to death but that is not normal

Any thoughts?