When to use an Epipen?

[fluffyhamster]

I'm in my 50s and over the last five years or so have developed a food intolerance (allergy?) to sulphites (I think).

At first I thought it was just garlic and was tested for that at hospital, but that didn't react as an allergy and the allergist said I might have a general intolerance to sulphites.
I've now noticed that sulphite-containing foods DO affect me - burgers/ breaded chicken/ wine etc so I try to avoid them. However I had a turkey burger last night (stupidly didn't check the ingredients) and had a bad reaction : swollen tongue, really cold/shivering, felt like crying, sleepy. I took an antihistamine and went to lie down then fell asleep for an hour or so.
I'm aware that some of those symptoms sound like the beginning of anaphylactic shock and I just wonder at what point I should have been more worried.
The GP has given me an Epipen in case of an emergency, but I'm not quite sure at what point I'd decide it was an emergency?
I was also a bit concerned that DH didn't check on me at all after I went to lie down - what if I'd passed out?

This is my son's action plan. For moderate allergic reactions like itchiness, hives, swollen lips we use liquid antihistamine Piriton - bit stronger than Piriteze (I've used the brand names rather than the drug name). If he's wheezing or his throat is swelling and he does not respond to his asthma inhaler then it's the epipen

Basically the minute your airway or breathing impaired is the time to inject

Thanks Puffty. You see this is what worries me - I had two of those anaphylaxsis symptons (swollen tongue and sleepiness) but didn't feel that I wanted to use an epipen and then need to go to hospital.
But I'm also worried I'm not taking these episodes seriously enough.
It's very confusing.
I wasn't having problems breathing, but I think my blood pressure had fallen, which is why I was so cold.