Regarding fear. In my life. fear mean!

Hello doctor, I am mother of 14 months old girl.first time mother..now a days getting lot of fear..I never used to get like these fear in my life before baby..this is very new to me..I am very much bold girl.i don't fear for anything.now fear only in my life.fear mean regarding my health.that I will die anytime..after that who take care of my baby.my baby will live alone without mother.i am nurse.but I don't work now.but I keep looking my mind symptoms..like giddings.impending doom..those time my fear is on peak...I really don't know.why my mind think of death all the time...death images...ex.if any Street dog howling I will get myths...I don't know how to overcome from this..everyday  I am my fighting with my mind.. kindly help me to overcome these issues