Hi, I had gone through your question and understand your concerns.
Weight of your baby is very less for age , you have not mentioned her birth weight .
Your baby seems to suffering from
gastroenteritis give her
ORS , zinc .You also need to show her to your
pediatrician early as she is weak and prone to severe infection without warning signs like
fever .
You needs to give her a balanced diet with variety , and supplements after consulting your doctor , Horlicks alone is not going to help , I usually do not recommend it .
There is also a need to find cause of her poor weight, was she born with
low birth weight , what diet is she taking , is her appetite poor or weight not increasing despite good appetite ? all questioned needs to answered and her diet to be planned accordingly in consultation with your doctor.
Hope this answers your question. If you have additional questions then please do not hesitate in writing to us.
Wishing your child good health.