The hefsek taharah has a different purpose than the bedikot of the seven clean days. During the seven clean days, you do internal examinations to establish that you haven’t had any bleeding that day. The hefsek, however, is intended to establish that you have stopped bleeding. Therefore, even if the first hefsek was pinkish, it just confirms what we already knew – that originally you were bleeding. If the next hefsek is clean, it confirms that you have now stopped. The fact that the moch was clean bears out this change in status. You may certainly start counting the seven clean days tomorrow.