Haunted Hotel? or not?

Me and my gf was staying at this hotel in the UK. It is an old hotel with old furniture in the corridors, but the rooms where quite modern. The first night I was constantly thinking of "what if we see a ghost" and just a few moments after that, she told me that she felt as if we weren't alone in the room. Later that night she asked me to stop whistling. But I wasn't whistling. Infact i was falling asleep. Another night we heard knocking. I thought it was the door but there was noone to be seen. We heard the knocking all night long and some of them where quite loud. Could this hotel be haunted? I tried to look up for haunted hotels but there wasn't the name of this particular hotel. What can I do to find out? any ideas?