temperature gauge/radiator

[94power_ranger]

my 94 ranger with a 4.0 has been fine then last night and this morning my temperature gauge will be cold then all of a sudden it will rise to almost high, then go back down. and i filled my radiator up the other day and this morning i had to put another gallon in it.
And there is this little drain hole thats leaking when i drive. its under the regular drain in the radiator but i dont think its supposed to leak

any help is much appreciated......thanks