Thank you for the query.
Your acute pain is caused by an abscess
due to pilonidal cyst
infection. You should not wait for your appointment as it should be incised and evacuated right away. Such abscess can lead to whole body infection that is why it should not be left alone.
The first step in such cases is just incision for pus evacuation. After acute inflammation healing, you can get scheduled for surgical removal of the cyst (probably the same you have had before).
Hope this will help.