No energy after work out?

I on my 3rd week of working out . Ive been dedicated . Ive worked out 6 days a week for an hr hr n half on treadmil. Doin 4-5 miles a day. I have no energy when im finished ive been showering then laying down only i cant sleep , im half sleeping half awake but body so tired. Wats causing this?will it pass? Its hard cuz im a in home live in caregiver for my grandmother who does not walk. So i have no energy to lift her.