Sick African Clawed Frog?

[amandaglad]

Hello,
I had a perfectly happy and healthy African clawed frog until a couple of days ago. He is in a 10 gallon tank by himself with a filter and kept at room temperature. His water is always kept clean and I cleaned it today.
His symptoms are: he's not eating anymore, he used to eat a piece of krill, now nothing. Every time he opens his mouth I feel like I can see that piece of krill in there but I can't tell. Obviously he's not like a mammal where I can just open his mouth up and see if something is caught in there. Is it possible that the krill is still in his mouth and it's taking longer to digest? Next, he used to be super active! He used to jump and attack at the sight of a finger by his tank and he used to LOVE belly rubs. Now he wants nothing to do with me and isn't as active as before.
Any feedback would be amazing!

Thank you!

[amandaglad]

In addition, today he seems more lethargic and is starting to form a bruise looking spot on his face. If anyone knows what this is and how to treat it, please let me know ASAP!