Latt, In general I always have my prescriptions in their original bottles. Sometimes I'm bringing in a 6 month supply. However I also always have, like my tourist I believe my pill organizer with a weeks. supply. If I'm in the State and I'm visiting for a short time on business usually I only have my pill organizers for a week or two. In this day and age if it becomes an issue there are pill ID on line.
I would say that technically they should be in original containers but in practice most tourist don't bring a 90 day supply say on a 7 day vacation and customs deals with this day after day. If you look and act like normal tourist you will not have a problem in my opinion. I never have and they have looked at my bags contents almost every time I arrive at BZE. I think they are more interested in me because I'm a Permanent Resident and I come and go two or three times a year.
I have always found customs fair and I have no real problem with the job they do. A few times we have differed on the valve of what I have claimed. I always claim low and remove goods from original packages but there was one incident when they thought I was claiming too high a value. That was a first. If your prescriptions are normal run of the mill blood pressure, cholesterol or such no problem. If they are opiates or such that is another matter. Come on down and have a good time. Smile and be polite even when an official might not be acting what you thing is reasonable and all is good. In my opinion. (after maybe 30 or more trips back and forth.
Somewhere on a beach in Belize