I had it last year and was in hospital for 10 days. For the first 4-5 months I was exhausted. The doctors couldnt offer anything concrete I could do/ take to improve things and told me to just rest as much as possible (not easy as a sahm to a 1yo and a 2yo) I thought I would never get back to normal. However, after 6months the total exhaustion finally lifted and now I feel just normal tired!
Walking is a good idea, but dont go too far. I lost a lot of weight whilst ill and all muscle. The shortest walk wiped me out, but I did force myself to take my two out in their double pram once a day to bulid myself back up. I think just getting back out and about in the real world helped too.
Good luck with your recovery. Dont underestimate how much it will have knocked you about and please, please take up all offers of help you get. Looking back I soldiered on more than was perhaps wise