This is a common wrong bidding of Gib which have not been fixed for long time.
What's 4♣? it exactly shows 4-6 distribution on ♣ and ♠,however I remembered 4♣ isn't forcing.Actually this kind of things rarely happen.
For this mini hand,after 3♦,It is best for Gib E to bid 3♥ with two cards support,even 3nt is better than 4♣.This is my solution.