3C was a mixed raise (7-9 HCP, 4+D), and 4D was a splinter (18-21HCP, 18+ total points, 1-D according to description)
Cuebids promise 1st round control in the gib style unless it has already been implied it is missing. Assuming it is not your style to open 2H with 4 spades, what do you do now?