Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain the symptoms of 
vomiting and loose motions after eating chicken sandwich seems to be due to FOOD 
POISONING..
It commonly occurs due to contamination of the animals with toxic chemicals, bacteria, viruses, parasites etc..
It causes when such contaminated  food is consumed leading to the symptoms like that you are experiencing..
As of now I would suggest you to take Ondensarton for relieving vomiting and 
Loperamide for loose motions..
Take 
proton pump inhibitors like 
Omeprazole for reducing acidity..
Take plenty of fluids and oral rehydration salts..
Do not starve and eat every after 2 to 3 hours and take more of banana, cereals, yoghurt, rice etc..
In case if condition worsen or there is no improvement consult an Emergency care centre and you can be given antibiotics, anti parasitic drugs , intra venous fluids etc depending upon the cause of the symptoms..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.