Need help looking for a certain yaoi manga!

I believe it is a story revolving two brothers being sex slave to pay off their dad's debt (not really sure why they were doing that) and...the younger brother does not know about this at first until he saw with his own eyes that his brother is having sex. The younger brother (uke) began having sex to the heir (?) Of the house they're living in. The seme and uke is attending the same school and is in the same class (?). At first, he hated having sex with the seme but I think, they became lovers...? At one point, the uke caught a fever (he didn't say it to the seme) because he slept without his clothes on. And in their lunch break at school, while the seme is kissing the uke, he realized that the uke's tongue is warm then he brought him t the infirmary.