My son had an anxiety attack 2 days ago then after he's been scared of it happening again and then today he woke up breathing super fast & racin heart?

Fear of having: another panic attack is typical with folks who have panic attacks. Visit your doc to rule out medical conditions and then see a clinical psychologist for strategies to help you manage this situation. Panic attacks are very treatable and are self-limiting. Peace and good health.

Need your son's age,: Neurodevelopmental & medical status & family history of anxiety disorders for specific answer. Panic Disorder = 2 or > panic attacks or 1 + 1 month worrying about having one. Cognitive-Behavioral Therapy is treatment for kids & teens. See pediatrician for referral to a child psychologist. A child psychiatrist may consider adding anti-anxiety meds after he's in regular therapy. See adaa.org.

Panic=Fear Response: The issue is to what? The body symptoms (rapid breathing, heart rate, sweating, etc.) commonly serve as a distraction, to the individual, & others, to avoid the issues driving the fears, issues the individual believes to be even worse; yet unspeakable/unsolvable, in the view of the person exhibiting the "pain attack". I.e. the label is a cover to hide something perceived worse. Uncover the issues!