Short version: don't worry about it, but don't repeat either.
Long version: Permanent damage is a function of exposure level and exposure time. Legal requirement for a workplace (OSHA) are 85 dBA for 8 hours, 95 dBA for 4 hours, 105 dBA for 2 hours etc. Pain threshold sits at about 115 dBA to 120 dBA. Some clinical studies suggest that these limits are actually on the high side but that's currently the law.
The most common damage is mechanical damage of the receptors in the inner ear (stereocilia in the cochlea for the Latin inclined). Sound waves actually wiggle a membrane in the inner ear and this vibration than wiggles the nerve endings which fire impulses to the brain. Excessive motion wears out the nerve endings and they die.
The limits above are obviously for adults, I'm not aware of studies that assess that for children or infants. However we can assume that a baby's ear is significantly more sensitive since the nerve cells are a lot smaller and hence more fragile. I would estimate at least 10 times more fragile which would mean to deduct 10dBA from those limits. To be really safe I would assume 100 times more sensitive and subtract 20 dBA. So as a general rule a baby should not be exposed to more than 65 dBA for 8 hours. 65dBA is about the level of a loud animated conversation.
[side note: babies have also have different frequency sensitivity curve than adults so the "A" weighting isn't really appropriate but we'll ignore this to keep it simple]
In your particular case, the exposure was very short. It really can't do any damage unless it was significantly above the pain threshold in which case your baby would have probably shown clear signs of discomfort. Also your baby was in a different room and walls and doors are quite good at absorbing high frequency sound. Even if it's ear splitting in the kitchen it's not all that loud in the bedroom.
At high frequencies even a small baby monitors can actually get quite loud, so this is something to watch for and avoid repetition.
On the ear wax: I agree, you should leave that alone and have nature deal with it, simply because there is significant risk to damage the ear drum or the middle ear when poking around in there. Ear wax is absolutely NOT there to protect against loud sounds. If there is so much build up that it actually affects the hearing, you need to have it cleaned out by a doctor.
Finally there is no point in going to a pediatrician since there isn't really anything she can do. I don't know whether you can diagnose anything at all at this age. Even at a few months old you can only check for major hearing problems at best.