It's not a cure by any means, but I've found that eating extremely healthy foods like avocado (high in good fat, zinc, etc) and eggs (high in protein), milk (calcium, vitamin D, protein), also salmon (omega 3's), nuts, fruits (antioxidants), spinach, etc tend to make me feel better especially if I eat it all regularly. They help me to bounce back from POIS much more quickly
Also, i am not a regular coffee drinker, but I have noticed that when I drink a small amount of caffeine either in coffee or in some soda, it tends to lift me from the POIS rut and helps me to forget about my symptoms for a little while. Of course sometimes there is a crash afterwards and it can interfere with sleep so you have to be careful....
take care