Regression? Or Normal?

Sometime last week, Henry must have had something occur that made him scared.  For the last week, he has not only refused to walk anymore, but also resisted standing.  If we put him in position to stand, he would be revving up and ready to take off before.

Now, he draws his legs up like he's afraid to stand.

Lori took him to the doctor, who didn't notice any obvious injuries.  I've surreptitiously checked out all of his muscles and joints, and he doesn't react to any touch as if it hurt.  So, like any 21st Century parent, what do I do?

To the Internet!  Which is, of course, a huge mistake all on its own.

I've gotten everything from toxic synovitis to the "onset" of autism (which, in and of itself, is suspect phrasing).  He is physically able to stand and jump -- that much is obvious whenever we put him in his too-small-for-him exercise saucers.  He just refuses to anymore, and seems completely gun-shy. Other Internetters have said that they've experienced this with their typically-developing children and that they got over it in a few weeks (!!!), with no known cause.

Another symptom that indicates a fear-based reason is that he seems very reluctant now to swan dive backwards out of my arms when I'm holding him.  Before, it was his rush, his adrenaline-junkie way.  Instead, when I leaned him back to begin that motion, he started clinging desperately to my arms to avoid falling backwards.

All I can think of is that he must have fallen or stumbled to where it may not have physically hurt him but mentally hurt him somehow.

So that puts us in a tough position.  Do we coddle him in the hopes that it goes away naturally and he regains his confidence on his own terms (with the risk that he won't and his physical development regresses), or do we act like Viper and Jester in "Top Gun" and keep sending Maverick up in the hopes that he'll get over Goose's death and engage?


UPDATE: Henry's OT and PT aren't worried about this.  They suggested that a huge series of rapid fire changes probably just overwhelmed the poor kid.  From me going back to work (when previously, I'd spent most every day at home with him), to switching bottles (he got the smaller 5 oz. bottles while we gave Evie his larger 8 oz. bottles so that we can increase her feeding), to potentially figuring out how to speak, to just the presence and increased awareness of a little baby in the house who's getting more of the attention that he used to get exclusively, and that he's approaching 2 years old probably all did it and something had to give.  They're fairly comfortable that he'll remember again when he's ready.