Traumatic ulcer on the posterior mucosa.

Hi Ma'am/ Sir, Around 12 days back , i got fever , sore throat, cough and body pain ..the feber persisted for almost 5 days with cough and sore throat..i took azithromycin 3 day course , ( felt like i had covid symptoms ) but all the symptoms got subsided . I started getting swelling above my 3rd molar in the buccal mucosa on both sides since almost a week , have difficulty in swallowing on one side along with chewing and pain on eaiting solid food ..i showed to one of the doctors , who told its a traumatic ulcer above the mucosa of the 3rd molar and its deep and painful..along with gum swelling and asked to get all my third molars extracted.he also told to ask for second opinion .. The doubt i have is what can be the etiology of this ulcer ? Is it due to my third molar or can be some other etiology as well... Pls clarify ..i am going to show it again on tuesday but before that i just wanted to know the cause for this .whether it can be of serious concern ?