First off I would definitely let somebody else look at it or go down to AutoZone and borrow one of their compression testers and check it yourself if you don't happen to have one. They are fairly inexpensive to buy and kind of handy to have.
There could be any number of reasons why you loose compression in a cylinder so the cause will have to be determined before the time and money required to fix it are known. It is a bit unusual for this to occur as described.
IF it turns out you have low compression in one cylinder before doing anything else check to make sure you have good spark from that plug - if you have a misfire or no fire that can cause unburned fuel to build up in the cylinder, erode the oil film and thus cause loss of compression. Hint - a misfire can mimic the symptoms of poor compression.
What does the oil pressure look like?
Pull the spark plug, shoot a few squirts of marvel mystery oil in there and fire it up, see if that helps in case you have a stuck ring.
Scoping the cylinder may also give you a tell tale which gives you a visual of the cylinder walls and top of the piston. If you can see scoring on the cylinder walls that's not good.
Checking the valve clearances my help you find a bent valve or excessive carbon buildup that may be interfering with the valves seating correctly.
I could go on and on, point being before that engine comes apart a competent mechanic has a bunch of things that can be checked with minimal time and effort that will be a good indicator as to what is wrong. A simple compression test is not sufficient enough to fully diagnose this problem (if one even exists).
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