Plz Help!!?

How to forget the dead..?I've lost my grandpa abt 3 months back...and its the first time i've actually felt the pain..coz i haven't encountered any such painful incident before..i am 17 now..and m not able to cope up with the loss...we shared a beautiful grandpa-granddaughter relationship...and i miss him terribly....and this incident has exposed my emotional weakness....hwat do i do...i have noticed few changes in me since 1yr--when i see some one celebrating or crying i automatically start crying..and i feel something in my heart...a tug u could say..like if a soccer player is celebrating his goal..i feel weird and tears well up in my eyes...what should i do..i feel moody and stupid with myself too...should i consult a doctor or something..??plz help..and i worry for the future too..i keep thinking what will happen if my parents too die and all my family too...plz help