I have anxiety but for some reason I don't feel like I relate to a lot of the way people describe their anxiety. I've often thought it must be something else but I don't know what it could be. 

A tense, jittery unease will often come over me completely unprovoked. my chest will get tight. my body gets weak. my head/scalp feels tense. it kind of feels like the inside of my body is crying or needs to cry, but not an outward feeling that I need to cry, if that makes sense. I've always interpreted that feeling as "anxiety" although I don't categorize it as an "anxiety attack". 

it usually will fade away after 20 minutes or so if I'm not in a chaotic environment, and then i will feel very calm and relaxed and at peace. 

I have plenty of things that I feel stressed or anxious about but they rarely affect me in the moment. the worst bouts of anxiety often come out of nowhere and totally unprovoked. it's very frustrating for it to come over me when I feel at peace, or doing a basic task that isn't directly giving me anxiety. I would rather feel this way doing something that would "trigger" it bc at least I could feel prepared for it. or I would know what to avoid. and I could enjoy my non anxious time without knowing it could hit at any moment.

is there something else this could be?