Wasn't there myself but a mate of mine did that tour a few years back and came home proper shaken. He doesn't spook easily either, been on loads of these things with me. Said he felt this crushing weight on his chest around the 4th floor and his torch kept cutting out even with fresh batteries.
That place has a serious reputation and not just the usual "ooh creaky floors" stuff. The TB death count alone is enough to explain why the atmosphere is so heavy apparently. Would be interested to hear what specifically happened to you though - was it physical or more just a feeling? And did any of your group experience the same thing or was it just you?