Thanks for the details.
A lot comes to mind when one talks about a red oral cavity. Fungal infections like oral candidiasis can cause this. Pharyngitis (sore throat) like a strept throat infection can also cause such symptoms.
Other than that physical agents like hot or cold substances that irritate the buccal (oral) mucosa can also cause this.
Gingivitis (gum infections) can be a cause of sore and red gums and can cause soreness of the gums as well. This is mostly related to a poor oral hygiene, alcohol, smoking etc.
GERD (acid reflux) can also cause irritation of the throat and oral ulcers and sores in the mouth.
In your case, this seems more likely to be a strept sore throat or oral candidiasis. What you need to do is to drink plenty of water to keep yourself hydrated.
Use a medicated mouth wash thrice daily and rinse properly your mouth and throat.
Avoid coffee, tea, fizzy drink and too spicy and hot and too cold food substances.
Follow up with a Dentist, throat swabs need to be sent for cultures. If this is an infection then this will need antibiotics which are prescription medicines.
A dentist will rule out oral candidiasis and gingivitis on visual examination.
Hope this helps.
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