Looks like ich to me too. I like using malachite green too. But know the lifecycle of ich. It is visible on the fish, then falls off into the substrate (why vacuuming is good!). Then it enters a free-swimming stage (this is the only stage meds can work & water changes help to reduce them) & then can reinfect fish. This is why some people think they have chronic ich, they didn't kill it all at its vulnerable stage.
Don't be fooled into thinking you're all done when you don't see white spots on the fish. Ich can also hide in the gills. I continue to treat for 10-14 days after all signs are gone. The directions will say 3 days or something, but that's NOT long enough.
I don't usually raise the temp (I haven't had it in years). There are heat resistant forms (people often use heat as an "only" treatment, no! IMO) & high temps mean less oxygen in your water. It can be stressful to fish that don't like high temps. Cardinals are pretty much ok with that, but do you have other fish that might not? Higher temps can speed the ich lifecycle. Like MaloK said, aeration is good. Change water & vacuum before redosing every time.
I agree, caught early & treated until really gone, ich isn't that hard to get rid of if you follow through. Fish can weaken & die from waiting too long to start an effective tx or from repeated reinfections from not treating long enough. 2 weeks or so of hard work & your fish should be ich free.
Good luck!