Ok, thanks for that reply Hurray.
I gave Amitriptyline another try, without taking any other vitamins this time, and with food as well, and the result is actually not bad. Today is my first day of POIS, and it is actually manageable. I would say symptoms are at least 60% better, and I can communicate with others relatively well.
Actually last time was similar; the reason I did not notice it fully is due to one side-effect of the drug being that it makes you really tired and groggy. I slept about 11 hours last night, best sleep in a long time (people use this drug for insomnia too) but it has kept me tired and groggy the next day (still, 5 pm now). There is definitely a noticeable reduction in brain fog, concentration, social anxiety, and the headache is less than usual.
The fact that it does help quite a lot with symptoms is uplifting, and it does lead me to believe that this 'type' of drug may be the correct one (for me), so Milnacipran or other SNRIs may be helpful too. Overall far better today than normal POIS. Having such a good sleep may also be at play here, and it could even be the sleep more than the drug, but either way it is the drug that helped to have such a good sleep.
Let's see how tomorrow (POIS day 2) goes.
That's all for now. Thanks again for everyone's help, and all suggestions for drugs to trial are welcome.