Firstly, pardon me for the title and do tell me if I need to change it, apologies in advance for this case.
Coming to the main part, next time you feel fatigue/ headache while listening to subliminal. Firstly, locate where you feel the fatigue. For many of you, you may feel it in your head. Feel it, notice it will have a density, it will have a heaviness, it will have a viscosity - feel all of it. Then lastly, it will have a flow. Come to this part only when you have done the first three. Now, follow this flow with your awareness and you shall reach the main sticking point/ emotional problem that is causing this fatigue/ headache. Now you can resolve it with awareness. After resolving it, your headache/fatigue should go away.
I would be grateful if you guys give it a try and let me know.