I agree...I would cancel the entire trip and reschedule another cruise in the next month or so, if possible. I have a 12 yr. grandson and he would be pitching a fit if he thought he wasn't going on the cruise, but 12 year olds don't realize what life and death really is. I wouldn't leave him at home, how could you possibly have a good time without him????
Hospitals in Mexico are nothing like you are used to here. The ones I have seen look like a convience store with a hospital sign in front of them, very run down, etc. Unless, you are very fluent in Mexican, or would get very lucky to have an American speaking doctor, how would you know what was going on?
My husband also had a flair up with his appendix several years ago, and his white blood count was also fine, but 1 week after his initial visit to the ER, he was in such pain that he was operated on and his appendix was also ready to rupture. Every person is different, but with your son already having a couple of flare-ups, I would really be concerned.
If you decide to go ahead on the cruise with him, I hope that you have a credit card with a VERY high credit limit, as someone else stated, you will be charged for any expenses incurred and then you can file with your insurance policy when you return home, but you have to have the available credit line to use for an emergency.
Whatever you decide to do...We all wish your son good health.