I lost my husband a few weeks ago and I cannot stop crying

Yes ? So cry, that is what you do for the first month or two. Find some support groups.

Hello, I am so sorry for your loss.You will cry for a long time,and when you think you've finished you will cry some more,it's the bodies natural healing process,although it doesn't feel like that now.
I don't expect you are getting any sleep either or eating properly.

My advice to you would be to visit your Doctor,who may give you something temporarily to help you get through this.

If you need any more support or you just need a friend,there are many people here who will be happy to listen... Takecare

Get support from your friends and family.