Hi My Grand Daughter Is 4 Yrs Old And As

hi my grand daughter is 4 yrs old and as had this cough for about 8 weeks. the cough is at its worst when she does any exercise or at night when she is in bed. she as been to the doctors and they have prescribed anti estimine and say its a viral infection. she coughs that much that she is physicaly sick. could you give me some advise on what we could do as she is loosing sleep andbecoming very distressing.
thanks in advance