Hello~I am sorry you are going through this depression. We have a wonderful forum for folks that have depression and issues like yours, you might be able to find the help and answers you are looking for by going there.
I will say, however, that if this continues, you really should see your GP, he/she may be able to prescribe something that will help bring you out of your sadness. Also, try adding a good, high potency B complex to your diet along with vitamins D, C, A and a good multi mineral, sometimes chemical imbalances in the brain caused bu not getting enough of the proper nutrients can cause this depression as well.
I hope you feel better soon.