Any BL where they switch? I have been looking everywhere literally

try "Like a tidal wave - from Pheromone Shower",

Dark Heaven
Love Replica
Neko x Neko
Wagging The Tail
Why Is It You?

http://www.mangago.zone/read-manga/neko_x_neko/
http://www.mangago.zone/read-manga/rise_of_moonsoo/
http://www.mangago.zone/read-manga/like_a_tidal_wave_from_pheromone_shower/
http://www.mangago.zone/read-manga/dark_heaven/
http://www.mangago.zone/read-manga/hatsujo_porno_star/
http://www.mangago.zone/read-manga/usachan_ookami/
http://www.mangago.zone/read-manga/wagging_the_tail/
http://www.mangago.zone/read-manga/afurete_shimau/ (they switch once at the very end)
http://www.mangago.zone/read-manga/playtime_with_hakdo/

Try this tag too http://www.mangago.zone/tag/Seke%20/