Post covid symptoms. Black fungus?

Hi, My uncle got covid symptoms on 8th Apr,21 and tested positive after a week and then few days later he was hospitalized for 2 weeks.. His oxygen level had dropped to 85 and his lungs got damaged to 50%. Later , He was stable and got discharged and he was not having any symptoms after coming home...only weakness he had... He is a diabetic patient and he was prescribed insulin but his Sugar level is not getting down(300-370) now... Other reports were normal... And we again consulted the same doctor he has doubled the dose of insulin... Also, since 3 4 days he is feeling bit headache in evening or night time and light fever of max 99 not more than that... Had also one day light chest pain 3 4 days back but for only once.. So, is that fine or we should worry abt or how much chances of getting black fungus?? Request you to suggest on this.