The one shot disposable ones (I use Howard Leight Laser Lite's) will certainly cut down on ambient noise. I have tinnitus in one ear (from a gunshot, not bike riding) and as a noisy day on a bike makes it much worse for a few days afterwards I tend to use them all the time. There's a whole range of different sorts of earplugs from hyper expensive custom fit down to really cheap cut from a roll foam and you need to find what works for you. In general though I've never found the custom fit ones worth the money and the 'umbrella' type (see below) are close to useless for bike riding (IMHO). The foam ones are annoying to fit but generally give the best results. Bear in mind that when your ears are blocked from receiving sound they do tend to respond by amplifying what sound they get. That can make tinnitus worse for a few minutes when you take the plugs out and your hearing seems supercharged.

Re ear pain, there's a few ways that could happen in my experience. Firstly there's irritation from the earplug material that could lead to some kind of allergic response or localised irritation. That's why I tend to use the branded ones rather than the 1000 for £1 ones on eBay.

Second, some of the non foam type have handles that stick out from your ear.
They look like this: https://uk.rs-online.com/web/p/ear-p...E&gclsrc=aw.ds
They're 'ok' for normal use but under a crash helmet the handles can put pressure on your ear and that can lead to a lot of pain. Plus they itch and move in your ear giving variable levels of sound reduction. Not for me any more

Thirdly - remember these things cut sound by blocking your ear. Block it completely (like some of them do) and you can't accommodate changes in altitude. Going up isn't so bad but coming down can be very painful.

If your ear pain comes from an actual infection it's time to get the medical profession involved. You don't want to leave it - ear pain is right up there with toothache and can have long term consequences.