Hello, My 2 1/2 Year Old Daughter Is Really Sick

Hello, my 2 1/2 year old daughter is really sick for quite awhile off and on. She haves Epstein Barr virus. She started to get fevers and fatigue and stopped eating much. She haves unexplained bruises on back and complain about her tummy. Please help me. I feel like my doctor isn't cancer about cancers or life threatening diseases.