Hi, I Was Prescribed Methylprednisolone 4 Mg Dospak 21 For

Hi, I was prescribed Methylprednisolone 4 mg dospak 21 for relief of virus infection. I'm also post mono yet still feeling extremely sick and fatigued. Am wondering if this is the right medicine to speed up the recovery or is it rather risky because labeling says "This medicine may lower ability to fight infections? Why than was it prescribed for infection??