Freak, I know it is hard to imagine ever feeling better. like orange said 24 days is not even close to enough time. Grief usually takes about 2 years to really work through. And thats if you are quote normal unquote.
One day you will realize you are smiling about something, then you are gonna feel guilty, "I shouldn't be happy, I should be miserable forever" but you will still slowly start to smile and laugh again. Things you used to enjoy may not interest you anymore but you will find new things that do. We, at my support group, call this the "new normal"
Would your granddad want you miserable? No! He loved you! he would want you to get one with your life and have a happy and full one. He would want to be in your heart but not holding it down. Be gentle with yourself. grief is an ugly beast......