The ache could be your liver or gallbladder, but the flush is *exactly* the same for both.
It could possibly by psychosomatic, but doubtful. Our bodies are constantly 'talking' to us, but we often don't listen, then when we start to focus on an issue, it seems the feelings are new. Most times, however, we've simply lived with and ignored the aches, pains, fullness, twinges, etc. for so long that we took it for granted that that's the way things are supposed to be. Actually, our insistence that everything is alright when our bodies are overloaded with toxins is much more of a mental mind game. =)