You need to take him to ER if you don`t get the appointment soon.
Small infants will be easily dehydrated if they continue to purge at this rate of 10 loose stools per day and if they do not take anything orally.
and Exhaustion suggest that he is dehydrated. So its a must that you see a doctor as soon as possible.
Have a check on his frequency of urination. If very less, it suggests severe dehydration
You may need to stop formula milk temporarily. If you are breast feeding him, continue to do so.
After seeing his hydration status, the doctor will advise admission for intravenous fluids or advise Oral rehydration solutions.
Please visit ER at the earliest.
Hope my answer helps you.