I read this not too long ago and I forgot the title. It's an omegaverse manhwa BL. The main characters are stepbrothers, the top is the older brother and the bottom is the younger brother. I think the younger brother suddenly presented as an omega where their parents are on vacation, the younger brother was about to tell their parents and go to the hospital but the older brother stopped him and said that he would take care of him (I think the older brother is afraid of losing the younger brother).
One scene I remember is that the younger brother and his friend (who's an alpha) followed the older brother and his omega co-worker in a hotel. And then, the younger brother got suddenly in heat so his friend checked in a room.
I don't know if this story is completed or not.
Additional info i remember:
the younger brother is still in college and is also working in a cafe together with his friend. Since his friend is an alpha, he had some speculations that the younger brother is an omega. Both his friend and his older brother hate each other.