Do a large water change (again, 90-95%) after the second ich treatment is complete, before starting fungus treatment.
I would recommend not using the Iterpet No. 8 anti-fungal and anti-bacterial treatment: apparently the active ingredient is an anaesthetic (or so I have heard), and I can't see how that would help with the problem.
(It would be best for the Corys if you keep all 6 or take back all 6, they do not do as well in smaller groups and their behaviour changes.)
I would recommend not using the Iterpet No. 8 anti-fungal and anti-bacterial treatment: apparently the active ingredient is an anaesthetic (or so I have heard), and I can't see how that would help with the problem.
(It would be best for the Corys if you keep all 6 or take back all 6, they do not do as well in smaller groups and their behaviour changes.)