Do not worry. My little boy is teething and he is very up and down at the mo. He has started to refuse to be strapped in the pushchair. It has happened the last three days. I went to play group today and he did it their. I was thinking, is it just me at the group with the problem. I just laughed it off and gave up and carried him to the car. I did not want to force him because I would of hurt, he was arching his back and sliding down.
Don't get yourself down too much, we all have our bad days.