Jeri
If there were only one red spot the on the day after the visit (day 2) that spot would appear. All the monks (except the one with the spot) could see a red spot and believe themselves to be safe. the only monk not to see a red spot would know he must have the red spot himself, and commit suicide.
If there are two red spots then those with the spot would see one red spot on day 2 and expect that monk to kill himself. The fact that no suicide happens on day 2 must mean there is more than one spot, so on day 3 two monks top themselves.