So as I have been developing allergic reactions I have seen how I am definitely not alone on our site for this phenomenon. I am thinking something that started our diseased state triggered histamine release. Perhaps a vaccine can. Maybe one vaccine does but you don't notice so then over time some susceptible groups get higher histamine release as the body tries a protective stance over foreign objects: vaccines. But those very vaccines or whatever caused low DAO. More and more this may slowly add up. Or other allergens besides vaccines may also have this effect of course. Perhaps the release of histamine from what our body thought was intruding effected our adrenergic receptors, possibly from the stress of breaking histamine down constantly over long periods of time. So the adrenal cortex keeps sending catecholamines: epinephrine and norepiniphrine to the adrenergic receptors. This may be why we get high heart rates, tired or painful muscles, fatigue among others. Our bodies may be in a constant loop! At first we probably don't realize this because we lack symptoms or are very mild and very sporadic symptoms as just being tired until it goes on over time, adds up and we have a diseased state.