Oh gosh!  Sorry to hear about Roman's episode!

That could be so many things.  Heat… like Goldengirls said.  Or the aftermath of a seizure or pain or who knows.  I would probably jingle up my vet and tell him and get his input.   

Lots of good thoughts.

My pug Tani never exhibits the behavior you describe around her seizures. 

A couple side effects of cortisone injections in dogs are hyperactivity and panting.  It sounds like it has been 5 or 6 days since his injection.  Has he had them before?  Did he react at all?  Could you call the vet and ask if he could have side effects from the injection 6 days later without having to take him in?

If its not that then what you describe sounds to me like he is responding to some type of pain. The panting is one sign- but the getting up like he is startled sounds like twinges or muscle spasms.  Tani also has fairly widespread arthritis and will sometimes wake out of a dead sleep like she was startled, and she stands with a hump in her back and her tail down which indicates pain.  She is deaf so it is not noises that wake her up.  She now sometimes chooses to lay on the floor instead of her bed- I think the firm surface is more comfortable for her.

I know Roman is a big boy, but can you take his temperature?  That way you would know he is not panting or laying on the floor because he has a temperature.

You could also post this question in the Ask A Vet forum to get Dr. Pam's opinion.

I hope Roman feels better.

Karen and the pugapalooza