[Lotrelf]

Yes,Pervinca, it was his illness in March. Though, why did he decide to go after that?

As for strength thing, I agree. From the text, it is clear that Frodo is NOT unable to fight. When they're in danger at Weathertop, it is Frodo who stabs Witchking. "He was hardly less terrified than the other Hobbits."(not exact quote, but it said something like this.) Before the Ring starts taking hold of him, it's him, among the hobbits who fights. Later in story, Ring gets heavier. We are given how it was affecting him i.e. He was the most weary among the three, He lagged and Sam had to ask Gollum to stop so that they don't leave their master behind etc.etc.