Well, there's nothing magical about 33 feet, that's just your standard 2 atmosphere pressure that makes calculations easier. What hurts is the relative change in pressure. So in shallow water, the change in pressure per foot is greater than in deep water:
10 feet = .29 ATA
20 feet = .59 ATA
300 feet = 8.85 ATA
310 feet = 9.14 ATA
Descending 10 feet from 10 to 20 feet results in about a doubling of the ambient pressure on your ear, but descending 10 feet from 300 to 310 is about a 3% increase in ambient pressure.
Hah! No idea, they were just the ENT docs specializing in ears that were within 100 miles of your zip code. I don't know any of them personally, and they probably wouldn't specialize in dive medicine. But for someone to check your ear, they should be OK if they are willing to see you. If you want a dive doc, you could try the DAN referral line.
No pain during the dive and I didn't have any problem equalizing, although I do still have a feeling of fullness in my ear. I've had that happen over the years (before diving, FWIW) where I've had that fullness sensation for a week or two and then it gradually goes away. Doesn't seem to be any rhyme or reason to it.
