First, let me extend my sincere condolences for your loss. Losing a parent is a very traumatic event.
I lost my father very suddenly in Dec 2015. I can tell you it was very traumatic and absolutely awful for the first year or more. During that time, I was so focused on helping my mother as I had such pain for her losing her husband who was relatively young and with such a sudden death, it really rips you apart. Dad did everything for mom so I had to help her with the bills, selling cars, transferring insurance etc etc.
After the trauma subsides, there tends to be a sense of longing that is very hard to describe as you go about you day to day life with your loved one missing. You still think about them often and miss their presence especially at holidays and milestones in your life and have moments of deep sadness, but the agony punch in your gut feeling will subside. The pain in our heart never fully subsides. It reminds me of a scab that trys to heal but when you really think about your lost one, the scab gets ripped open and the pain reappears as it was the day you lost them.
My father's death has changed my family's live drastically since he passed. His birthday falls on father's day so this year will be very hard. He was the anchor in all of our lives and full of so much love and life before he passed. It was so hard losing him suddenly with no prior illness. Staying very busy helps and focusing your attention on helping others and trying to find the gratitude in the time you shared with him while he was here and holding your memories dear will help. I know how hard this time is. Try and remember that love never dies. Your mom will remain in your heart forever. Rest and make sure to take care of yourself as well while you are healing. Again, I am so very sorry for your loss.