Feeling very low

I’m in the middle of switching my domain. Luckily, I already have an offer in my current field, so I’m serving my notice period. The new domain is completely new to me, though I recently cleared a certification that’s pretty in demand — so I’ve been getting interview calls. The problem is, I’m feeling really underconfident and scared to face the interviews. I’ve got around 50 days left in my notice period, and honestly, I’m feeling pretty low right now. Any motivation or advice would really help.