No big deal here but last night I started getting earache and a bit of sore throat near the ear.

Bad enough to take a paracetamol.

Any point in buying some cheap Thai ear drops or is it behind the eardrum and no point?

ps have not been swimming lately....not likely!

I use 3% hydrogen peroxide solution to clean ears.

Buy the cheapest ones you can buy......

If the pain is inside the ear (as seems likely given the accompanying sore throat) then likely an inner ear infection. Ear drops and peroxide etc will have no effect.

See a doctor. You may need to take antibiotics.