Thanks for asking I gone through your question, your 6month old baby whose was low birth weight is now 5 kg. and she having itching in ear. She is on pediavit and fenistil. First I want to say you that she is gaining weight as per expected, so her care giver is giving good care. her weight is triple from her birth weight. you can give her multivitamin drop pediavit, . As her age is now 6 month , now start giving complimentary feeding like mashed banana, gruel of rice or weight or pulses. there is harm to give drop fenistil to relieve her congestion , hope i answer your query