Thanks for sharing your concern.
As your history suggest you have gingival (gum)enlargement.
orthodontic braces impingement could be the reason for this in your case.please check it with your dentist
and get it corrected.
sometimes this is seen in vitamin c deficiency
too.Also poor oral hygiene
aggravates this situation.
This gingival excess is removed by gingivectomies and gingival surgeries.
your gums have started healing thus appearing whitish.
Visit to an orthodontist regarding mouth sores on cheek ,it can be due to trauma from brackets .
meanwhile you can apply Dologel ointment over the affected area on the cheek .
Scaling and polishing should be carried out periodically.it is must in patients wearing braces.
maintainence of good oral hygiene will help you achieve faster correction of you teeth.
hope it helps.