My 2 month old randomly started crying hysterically and...?

I tried EVERYTHING I tried feeding her, burping her, changing her, giving her pacifier to her, rocking her, swaddling her, and NOTHING worked. I felt so lost and had no idea what to do. When her dad rocked her, she fell asleep. Has this happened to anyone before? I mean when she cried like this, I never heard her cry like this before. It scared me half to death. I feel like I should have been able to calm her down. Also, does the worrying to death ever stop? I feel like I am worried about everything, especially SIDS. I try not to think about it, but I always do. I can barely sleep because I am constantly checking her even though she sleeps throughout the night! So, any ideas on what this random burst of hysteria was, any similar stories, and does the worrying ever stop?