Minor setback

About a week ago (actually on my bday), Griffin had a run in with the toilet seat lid that left him screaming and his "parts" dark purple. We called the dr and luckily he said it was fine as long as he could still pee and it didn't swell up a bunch. Finally later that night he went to the bathroom and said it didn't hurt anymore. I thought we were in the clear then. Well, he had a delayed reaction... about 4 days later he started being very scared of the toilet and had a few accidents (on friday night he peed his pants 3x at McD's, luckily it's right by Target so I ran in to buy new undies). Now he's using the potty again, but is still nervous and INSISTS that Mike or I stand there and hold the seat and lid up with both hands. He even watches Thomas in the bathroom and warns him about the seat. I'm hoping this passes soon. I'm not real fond of putting both of my hands on the seat so often!