I went through 4 days of extreme drug abuse, no sleep, and strenuous exercise that triggered some irritation in my heart. could this be myocarditis?

Be seen!: I am glad you are concerned that your activities may have caused some damage to your body, as those activities are likely to "get you" sooner rather than later. More information is needed to know if you may have myocarditis. Usually that has chest pain/pressure, fever, shortness of breath, and certain changes on your physical exam. Depending on what you mean by irritation, it could be many things.

Seek Medical Help: It is very difficult to provide you with any specific diagnosis based upon the details presented in your question. Given the fact that you have concern for your heart is enough to warrant an immediate appointment with your primary care physican or a trip to the emergency room. Less emergent but none the less important is your report of drug abuse. Talk to your physican. There is help. Good luck.