It's possible that the source of moisture was something other than a leak, but yes, if it is from a leak I'd think it would be in that general area.
I went through the same thing back in April. Submersible pump grabbed on to bottom of liner and screw head pierced it. Water very quickly began surfacing outside of pool, so knew something was wrong. Food coloring was like you said a mess so I just kept feeling with my feet, diving with a mask and was very deliberate and systematic in trying to examine the surface area and finally found it. Not sure if a small hole in the side would lose water at same pace that one in the floor would, but are you noticing abnormal loss of water?
When I replaced my liner there were rust spots all over the place on the inside wall and they could not have all been from leaks. I'd look for more evidence that you have a leak before calling a detection company, which sounds expensive!