You have accidentally damaged the tympanic membrane (commonly called purda or eardrum) by the ear bud. As the specialist told you, it may take a long period for a complete recovery, which is possible. It is important to avoid infections and further damage to the eardrum and the part of the inner ear behind it, which has a crucial role in hearing and body balance. If not well cared for, the child may develop deafness. It is important to check up the ear drum periodically by the specialist. You have now learnt a lesson: do not use ear buds in small children.