i dont understand my leg .

i just got home from walking and i'm miserable. my left leg feels like shit, i just finished my 5 day pulse steroid treatment but i feel worse?! My left leg hurts like hell and i get aches when i walk. But my leg strength was 4-4.5/5 when i got discharged 2 days ago. And even then i had this weak feeling in my leg and aches. i dont understand it. i had a relapse that my right leg 's strength was 3/5 and i did not even feel a thing when walking. So why am i miserable right now when my leg is not that weak? i'm in a really dark place and i feel like a fraud. i want this pain and discomfort to end.