Can anxiety attacks happen without even knowing or worrying about stuff at the time it hits you? if so, does the subconscious mind play apart in that?

Surprised by Anxiety: Yes, anxiety attacks can come out of the blue. Call it unconscious or a conditioned response, in any case something triggers it. Healthy lifestyle choices in eating, rest, and psychological support offer lots of hope for folks dealing with this. The very best to you.

Focus on Breath: Your mind can work too hard. Sometimes w/out results and you feel even worse. What is called 'anxiety' includes physical sensations that can arise biochemically w/out meaning - or, there can be lots of meaning which you can accept or deny. But it's not too useful to 'think' at that time. Before/later is good to think. But, then - focus on a neutral dot and breathe. Therapy/meditation may help.