Wherein I feel like a failure

So it was that just after 10:00 this morning, I had a parenting crisis.

We were at church, Liam and I.  He had woken up so early that he was tired by the time we left for church, which was not a good sign, but I stuck him in the stroller anyway and hoped for the best.

Primary lesson prepared (with handouts!) - check
Tithing - check
Diaper bag with extra books and snacks - check
Arrive early enough to sit on the end near the door, just in case - check
I thought we were set.

During the first Sacrament Prayer, Liam smacked his head on the corner of the arm rest.  I took him out for a few minutes, then came back in to try some books.  He started hollering again.  So I took him AND the bag out and after a lap around the church, I put him down to walk by himself.

It wasn't long before he had walked into a dark, empty classroom and shut the door on himself.
AND THE DOOR WAS LOCKED.
Commence Screaming.

I hurried to the library to ask if anyone had keys.  No.  I ran to the clerk's office.  Someone was there, and luckily, he did.  My son came out with tears streaming down his face, terrified and exhausted and feverish (because he has canines coming in, of course!).  Try as I might, I couldn't get him to calm down.

10:15 and I have to decide.
Stay and try to teach a lesson?  Wait until the end of Sacrament meeting, so I can at least make arrangements for my class?  Take Liam right home and leave them high and dry?
After chasing him around and trying to keep him quiet, I'm not feeling too good myself.  I'm getting light-headed and nauseated and having those oh-so-familiar contractions.


I chose the third option.  After some Tylenol and a bottle, he slept for over 3 hours, which NEVER happens.
I still don't know though.
What would you have done?