Weird Leak (I think???)

[Slimsey]

We have an above ground pool, approx 4 years old.
This year we noticed the water level has dropped LOADS. (about 2 inches water left in the bottom of the pool)
We started refilling it, and noticed an area around the pool which was really water logged.
So I climbed in and found a hole in the bottom of the liner about 1/4 inch long. (If I pushed around the hole, dirt would come through into the pool) So I patched the hole. (actually had the pool company come out and patched it and looking around the rest of the pool could find nothing else)
Looking around we could find no other holes or tares. So we started refilling the pool.
After 6 hours our water logged area was still no better, so we stopped filling the pool and left it overnight. During the night the water level dropped about an inch and the ground was still waterlogged. So we assumed it was still leaking.
Throughout the day however the ground dried out and the water level didn't drop anymore.
We have started filling it again and so far so good, the water level has now risen another 4 to 5 inches, and the ground is not water logged.
So, do I have a hidden leak somewhere that keeps plugging itself?
Or is it possible that the sand under the pool was completely waterlogged, and the weight of the pool after patching and refilling was squeezing the water out (like a sponge) hence causing the soggy ground.
Also the water level dropping caused as the pool sides returning to the correct shape (after caving in a little due to lack of water)
Or am I just kidding myself, time for a new pool liner?
There really are no visible holes, and I've gone round on my hands an knees looking!
Is there a way of detecting a leak (other than the lowest water level point)

Thanks for any input.

Slim