Everytime i get a cold, anxiety get worse. afraid not to breathetc. and when i see a spider, i'm afraid its bite can kill me. is this irrational fear?

This is usual fear,: It is usual fear until it interferes with functioning.

Likely is: Sounds like anxiety to me but its sometimes hard to know where to draw the line. Consider consulting a psychotherapist to evaluate it. Meds can definitely help if needed.

CBT: Seek a cognitive-behavioral therapist who specializes in phobias. One method they use is systematic desensitization which slowly and incrementally brings the person closer and closer to the thing they are afraid of in slow, graduated steps that help make the anxiety more tolerable.