it is most likely that he is having g i infection and needs immediate treatment with i v medicines and infusions.
Please take him to emergency and get a check up and start on treatment .
If he can take oral medicines and no vomiting
you can start on brakke tab 1 tab 2 times after food .
ds 1 tab daily .For pain decolic tab 1 tab may be given three times .
Better will be to take immediate medical consultation .
hope you be all right soon