I was on bed rest during pregnancy prior to my birth too but at home. I had the same stiff feelings and old person feeling too and very, very low immunity after my son was born. I was very sick until I began improving my nutrition. Don't count on vitamins to help any of that. If fact they can be harmful as they are artificial, isolated, nutrient and not really nutrients that you might get from foods.
Please try increasing your spinach and other fruits and veggie with iron. Broccoli has more calcium, more Bioavailable to your body than any milk products. Eating a variety of 9-13 serving fruits and veggies each day will help almost every issue you are having, so do as much as you can. If you just can't eat that much, then get a whole food supplement that contains only fruits and vegetables (preferab;y a reputable one)
Along with that you will need to do some weight bearing activities when you are able as it's the only other thing to keep your bones strong. Just do it gradually. I know it seems so frustrating now,, but you will be your old self again.
Hope that helps, God Bless