Please help / antifreeze leak

First thing I wouldn't recommend putting any sealer in unless its a road side last resort. The only things I can think of that may be leaking are 1. Freeze plug 2. head gasket 3. exhaust end stud 4. Back intake gasket. I mostly use UV dye and a mirror to check for hard to find leaks. If you can't see back there with a mirror then I would get a paper towel and fold it to say a 3''x3'' then hold it behind there to find the leak. On a cold started engine work from the top down, when the towel comes up wet then there is your leak.