Has anyone heard of this related to an allergy?

My 9 month old daughter has recently tried toast (whole wheat) but for the past few weeks here voice has has seemed crackly. Personally I think it's because she does these very high pitched squeals and screams when she gets excited, my MIL is convinced it's an allergy, even though my daughter is extremely happy and acting normal and has no signs of an allergy (watery eyes, runny nose, rash, irritability, being sick) I do have a check up May 25 (earliest I can get in) I really don't think I have anything to worry about, but she (is staying with us for a week) is so convinced something is wrong with her and telling me to stop any foods, except for beginner purees, it's kind of driving me crazy that she thinks I don't know my daughter well enough to know when something is wrong. Has anyone heard of a baby having a slightly crackling voice as an allergy reaction? I haven't read it anywhere