how do I work out what im allergic to?

[Realitea]

I have a sore patch on my eye which ive been told is dermatitis. Now its on the other eye and its so itchy and makes my eye swell. Ive changed all my make up as I wear it every day and I take it all off every night with 'simple' products. How can I work out whats causing it?

Try a few days makeup free. If it clears up then it may well be your makeup.

Don't wear anything until it clears up
Them wear each makeup item on it's own until you get a reaction

Why hadnt I thought of that? Thank you!