The word I'm looking for is similar to "claustrophobia"; it's to describe the feeling of being trapped in a place that feels too narrow, almost like you can't breathe properly in it. (A noun, preferably not a -phobia one.)
Stenophobia is the irrational fear of narrow things or places. Someone suffering from this condition can expect to experience a very high amount of anxiety from merely thinking of narrow things or places, let alone actually seeing it. In fact, their anxiety may be so intense that they may even endure a full blown panic attack as a result of it. Although such an influx of anxiety will not always be the case for everyone suffering from stenophobia, it is still very plausible to occur nonetheless.
From Psych Times