The spoiler found in below website, doesn't know true or not.
http://www.latestgossipwu.com/gossip-10551-a
Naina is feeling guilty that bcoz of her karan is suffering from allergy. Even though
Naina has personally bought organic colors for karan but it got changed and he gets affected. Later Naina finds the colors which she bought is exchanged by sandhya and she presents her doubt in front of karan were he bursts out his anger rage for doubting sandhya with such cheap plan.
I think Even though Naina is good if this spoiler is true then naina will be taken this decision emotionally bcoz karan gets angry on her due to allergy and later she finds organic color in store room and servant informs her sandhya was in store room and by emotionally she thoughts to share this with karan but karan burst at her again.
I wish this spoiler shouldn't be true bcoz naina knows if she has to do something then it should be done with proof but lets us have to wait and see how and were it proceeds to but for naina its not easy task so she should cleverly play the cards regarding sandhya and I don't think naina alone cant do this task so its better to share with meghna. Even she had expired medicine proof also. Blaming sandhya is not an easy task for both the sisters lets wait and see and hope for best