fatigue managment rebuilding wasted muscle

Sorry - accidentally titled my first post 'questionnaire' which was a bit confusing, so I've done it again.

I'm recovering from an av fistula in my brain. It caused pressure for about 6 months before being operated on. Recent MRI suggests I still have 6 to 12 months of possible recovery.

It caused a creeping paralysis in my lower body and forearms and as I weakened I was unable to walk from last may and I have a partial loss of feeling in those areas (can feel touch but not hot/wet/cold).

I was in rehab ward from July to October and managed to progress from wheelchair to frame. I can now walk max10-15 meters with frame. I think I have sufficient nerve control back because I've seen everything move at some point. I'm now struggling to strengthen wated muscles.

My question is about how much or how little I should be doing. I get some days where my legs feel like lead but I can't connect it to a period of extra activity or inactivity. Is this normal to get ups and downs? Should I rest during them or try to work through them? My right leg and foot is weakest and I'm having trouble starting my ankle dorsiflexion although I can wiggle my toes a bit.

Any advice would be gratefully received.