Battery drain but on answer in fuse panel

[Orence1]

Replaced my optima battery a few months ago thinking it was gone (10 years old). Bought a new Optima. The old one is sitting on the bench and I decided to check it with my meter 2 weeks ago. Shows 14.2. (I had it on the charger when I swapped it out.) It dawned on me that I may have a current drain. Sure enough, went to start the truck yesterday and the new battery was almost dead. Did the fuse panel thing today with the test light hooked up to the negative cable and none of the fuses removed showed a faulty circuit . The exact same thing happened a few years back. None of the fuses removed caused the test light to go out. A friend who is sharp with wiring discovered that it was the aftermarket radio. This fall I had a local stereo shop install a new stereo system. Is it possible that I have the same problem? It just seems odd that after several months the problem is now showing up. I did start the truck periodically over the winter with no issues. I am at the point now where the battery is almost dead after a week and I had recharged it fully with my battery charger. I am hoping that somebody has run into this issue and can point me in the right direction. Thanks in advance.