Post Covid Condition. Duration again?

Hi, My grandmother was discharged from hospital on 11th Nov after being treated for Covid. She was fine till 3rd Dec. However, suddenly she had a temperature of 103 F and complained of breathing difficulty and chest pain. She was given Dolo yesterday and also today in the morning as well. Her temperature is now normal. There is no chest pain as well and she is breathing normally also. Oxygen levels have been in the normal range throughout (95-96). However today we noticed a sore/bed sore like around her hip/rectal area. The area is quite red. Post discharge, she has been quite weak and is not able to go to the washroom at regular intervals. Feeling quite weak in the legs. There has been no outside contact for more than a month since we are in containment zone. I wanted to ask can bed sores cause the above symptoms? Also, if a person has tested negative, then can that person get reinfected in such a short duration again??