My 20mth Older Daughter Has Been To The Doctor Twice

my 20mth older daughter has been to the doctor twice this week and they can find nothing wrong other than allergies. her chest xrays came back good. but she has started running a low grade fever and coughs and gages when she sleeps, she gasp for air sum times, and she also does all this when she cries. she is keeping her hands in her mouth and not eating good