Prolonged effects of vertigo

My father is a 57-year old male with type 2 diabetes. A month ago, he had, what we suspected as vertigo because he was vomiting and he said that everything was spinning in which he could not even sit up straight, without someone supporting his back or else he would collapse. Symptoms included blurred or double vision, slurred speech, imbalance in coordination and loss of control in motor function. When he was first sick, he was very weak and we called for a house call doctor and he administered multiple IVs for my father and his blood glucose level was at 17.8 mmol/L (before breakfast). The doctor advised him to rest and get his blood glucose level under control. He was taking metformin to reduce his blood glucose level and we started to monitor his meals and sugar intake. After a week or so, we had his blood work done and the results came back with his cholesterol level of 7 . Before this, he had normal cholesterol level and we regularly check his blood pressure which turned out to be normal too and there is no known family history of heart diseases. He also sustained an injury on his leg, a quite severe burn specifically, from the thermal massage bed which took so long to heal.

And now, a month later, we managed to control his blood glucose level with the average of 8.0 (before breakfast), and even at one point, the lowest it had ever been was 6.8, but there were still no major improvements to his condition. He regularly takes his meds, he is on casprin, metformin, cholesterol meds, (crestor rosuvastatin & simvastatin). He still has not regained his sense of balance, he still cannot walk because of the numbness in one side of his legs and arms, and his speech is still slurred and garbled. He also experienced occasional series of dizziness although not as severe as before, and sometimes, difficulty in urinating. Although there are some minor improvements such as his arms and legs do feel ‘lighter’ and he was able to lift them up by himself, occasionally and he was able to sit up straight on his wheelchair for hours. My family is worried and unsure of referring him to hospitals due to the current covid situation but we are running out of options and this has persisted for too long. Please help me. Thank you.