Tylenol... concentrated infant's Tylenol.
I know you want a homeopathic remedy... and I'm sorry I don't have one. but Tylenol or Motrin works... and ultimately that's what you want.
I prefer natural methods for myself over drugs too, honestly, (melatonin to help me sleep, pantothenic acid to improve my skin and complexion, vitamins to boost my mood and metabolism, valerian root for anxiety, etc.) but I would not put anything in my baby that it's manufacturing and quality control isn't regulated by the FDA and been tested for safety.... jsut remember, from nature, doesn't always mean it's safe. Perhaps you could seek the advice of a homeopathic doctor who has many years experience treating babies without traditional 'medication'.
Just be careful what 'natural' remedies you use... and keep in mind,... the cold medicines that were recently pulled from the shelves, was not necessarily because those medicines were unsafe... but the parent's who administered them, didn't follow the directions, and inadvertently overdosed their children...