[JaKe Elite]

pawn Код:

if(params == "health" && SDay == "health) return SendClientMessage(playerid, COLOR_GREY, "The day is already on day of good health.");

should be

pawn Код:

if(!strcmp(params, "health", true) || !strcmp(params, "SDay", true)) return SendClientMessage(playerid, COLOR_GREY, "The day is already on day of good health.");

You can't use string as integer.

So you have to use string comparer (strcmp).