Let me ask a few questions about Tex:
How long ago did Tex lick the cortisone cream?
What was the cream applied to or did he chew the tube?
How is he acting funny?
Normally cortisone cream will not make a pet sick, especially in that small amount --but every pet reacts individually to any type of medication just like people do. I would go ahead and rinse out his mouth with copious amounts of water. You can squirt it in there with a dropper or syringe. Make sure and rub a qtip or something up around his gums and inside his cheeks to clean any residue.
You can give him some benadryl in case he is having an allergic reaction to the medication. Let me know his weight and I can give you a dose.