I Have 11 Years Old Daugther, Last June I Brought

I have 11 years old daugther, last june i brought her to her pedia dr. And notice she has pale skin color in her lips..so she asked to do blood test and smear blood test.. after blood test resulst came it show my daughter is low hemoglobin.. and the pheriperal.smear result is normal. The dr. Gave her vitamins for three months and she say comeback for followup check up..after three months.. the make blood test again.. and my daughter blood test still low but went up just one point. 8.57 to 9.57 and the dr say give refferal to hematologist.. they went to hematologist. And hematologist asking if she has fever pain in the muscles..all nothing she is eating a lot more energy she dont feel anything.. and the hematologist say she will make bone marrow test..
Is there any test to figure out why my daughter causing for her low hemoglobin?