I can't wear earplugs at night because I wake up those symptoms described.
But, on the other hand, I do think think that you may have a slight ear infection. As a swimmer and surfer it sounds pretty familiar. I've had countless ear infections.

If your ear hasn't progressed to swelling, redness, pain and major sensitivity I would try the following first. Have you done a hydrogen peroxide rinse? Go really slow... put only a tiny bit in your ear to clean it... it will sound and feel like fireworks and is a weird sensation the first time. Don't over do it. A couple drops is fine. Also, you can try the rubbing alcohol and mix it with parts water to drop in. Finally I've always done this before PCS but it could be contraindicated now... lie down and put the blowdryer next to your ear to dry it out (low setting). This works wonders but the sound might be too loud.Then maybe you need antibiotics.

I have to switch out my earplugs a lot because as you know anything extra with PCS like a earache can be awful. I just buy the big jar so as not not feel bad that I go through them that fast. Oh and taking baths helps me so much with my pain. Sounds like you just have some left over water in there. I have had a couple ear infections since my PCS (mostly acquired from the pool) and they have increased my overall symptoms. But, they went away without antibiotics. Best wishes!