Cleaners (shrimp or wrasse) aren't really that effective. Not much is except copper & hypo in a quarantine tank.
Ich has 4 stages of life I believe, lasting 4-6 weeks and only one of which presents visibly. Many people try various treatments and see the ich disappear thinking they've cured it. All those "ich came back" posts you see are really ich that never went away; just left the visible stage.
If your fish is strong & otherwise healthy, the ich can come & go on its own. If its present in one fish, it's present in all fish so they all need to be treated outside the tank.
One positive note: unless a new strain of ich is added to your tank, the ich cycle will end in about 11 months & be unable to reproduce. BUT treat it. Imagine you had a full body rash 24/7 for 11 months - you'd be going nuts. In that time, if anything else pops up like stress, water quality problems or another disease, it'll probably kill the fish.