Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain acute vomiting and diarrhea can occur due to a number of causes like bacterial infection of stomach,
stomach flu, parasitic infestation, electrolyte imbalances,
food allergy etc..
Dry mouth and lethargy seems to be be due to loss of water and electrolytes due to loose motions and vomiting..
You should start taking Fluid Replacement Therapy that is drinking plenty of oral rehydration solution and other fluids to replenish water and electrolyte in body..
Take more of banana, yoghurt, cereals and rice..
You should eat every after 2 hours..
You can take
Loperamide to reduce loose motions and Ondensarton to reduce vomiting..
In case of no resolution
consult a Gastroenterologist and get evaluated and a thorough clinical evaluation can help in diagnosis and treatment can be done accordingly..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.