coolant leak in my 93 cavy

about a month ago while stopped at a stop light on a hill, when the light turned green i hit the gas pedal only to feel like i was in neutral. so i made my way over to a parking lot and stopped the car, furiously i popped the hood tryin to see if i could tell what was the matter, even tho i knew i wouldnt be able to tell. i let it sit for about 2 minutes and started it back up again and it was fine. this happend 2 times again in the same week and all i did was turn off the car, then restart it and it was fine. so i checked my fluids and noticed my coolant was gone, so i put in coolant w/out adding water and it seemed fine. next day it acted up again.someone suggested the filter,so i got a new transmission filter and new trans fluid, drained the old fluid and changed the filter. took it for a test run and it was fine. it ran perfectly for about 3 days and then it started to mess up again. checked fluids and once again no coolant, so i got more coolantand this time mixed in water with it and put it in, left the car running for 5 minutes and then got in and put it into reverse and nothing happend. after talkin to a few friends they said i must have a coolant leak and it is gettin into the transmission, whats the cheapest and quickest fix for this bc i have been without a car for a month and it is killing me. by the way im a senior in high school with no job bc of sports, so thats y i couldnt take it ne where

when you changed the transmission fluid did you see any coolant in the fluid?

well it did seem pretty thick for trans fluid, im not much of a car person so i wouldnt kno if there was ne or not