Mayo Clinic says...
Though a warm sitz bath and applying ice seem contradictory. I do know someone who did the sitz bath thing when she developed hemorrhoids during pregnancy. On the other hand if sitting on a bike saddle is an issue, that implies inflammation which I would treat with an ice pack, I think.
Not mentioned on the Mayo Clinic page, but I think my friend also used a stool softener to prevent further irritation.
I hope they subside soon.