I believe it's generally agreed that it takes people up to three months to adjust to a new workplace and job. In that time, different situations can leave us feeling ill at ease or even incompetent, when we may in fact not be.
What sort of conversations do you hold with yourself before the panic attacks come? Are they self-reproaching? Or are you perhaps guessing that the other person thinks you incompetent? If you can zero in on the typs of inner responses you feed yourself in some situations, you may then have something to work on to cut down on the panic attacks.
Are there some situations that occur where you could say, "Let me think about this for a little while and I'll get back to you?"