As described, your iPad battery may be expanding and undergoing a critical failure
1) Immediately discontinue use of your iPad. Do not attempt to charge your iPad. Keep the iPad away from any combustible materials - in a cool dry location.
2) Seek advice directly from Apple Support. You can contact the Support Team using the Support using this link:
Official Apple Support
Alternatively, you can initiate and manage your support cases from another Apple device using the excellent Apple Support App. If not already installed, the App can be downloaded from the App Store:
https://apps.apple.com/app/apple-support/id1130498044
Otherwise, would be best advised to visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad:
Genius Bar Reservation and Apple Support Options - Apple