Way In Over My Head, What Have I Done

Just started my first IT job about a week ago as Level 1 HD, they put me on the desk today as they had trouble setting me up last week. Today was absolutely awful, many people calling and asking for help and I knew nothing! I have the comptia trifecta and it just feels like it was a waste. I'm on probation for 6 months and I just feel like I'm making a fool of myself, look like an idiot and this job won't last because of how much I'm getting in the way. Its a low paying job (32,000) and I'm spending about €400 of it on travel each month.

I love tech and building pc's and overall just see myself as a giant nerd but now I think I overestimated my capabilities and genuinely feel like crying and giving up. Maybe this field isn't for me.