I think I am having an anxiety attack and idk what to do

I can’t say why I feel this way. I have had some tough things happen in the past which have made me very insecure about myself. This is especially very true about my relationships. I am currently in a very happy relationship with my bf of over 1 year, but my past keeps creeping up and making me doubt myself, him, everything. Due to some work related stuff we will not be meeting for the next 3 weeks (longest so far) and it has made me so scared of everything. We don’t generally chat too much, but recently he has been even less chatty (I know this is because of work and health issues).

All of this combined is making me panic in the very moment. I feel like I am going to start hyperventilating any moment now.. I feel so scared and lost. Idk what to do..