In Portuguese it seems more natural to use "Estou com dor no peito."
why can't we say my chest hurts
That would be "Meu peito está doendo" or "Meu peito dói".
What is the difference between sore chest and pain in the chest
I would say that pain in the chest hurts more. Sore chest is just a little pain.
this is the first time I have heard the "t" in peito pronounced as a "t" and not as a "ch". Are there rules or information for pronounciation?
You should say the letter "t" like "tch" when you have "ti" or when "te" comes at the end of a word. It works for some regions in Brazil.
Many thanks. I wonder if Duolingo had thought of including an initial section on the basic pronounciation of the vowels and consonants that don't sound as one expects?
You should try the Forvo website. You can type in any word and it gives you various pronunciations by natives from different parts of the world.