I had strep throat and took antibiotics irregularly. During this period, could my immune system have attacked my heart very mildly?

Define "late" Studies show you have up to 10 days from the onset of fever to start antibiotics and stop rheumatic heart disease/fever. You likely have only 5 to stop kidney related issues from nephrotoxic strains. When you post a question, the more data you provide, the more specific we can be.

Related Questions

Are there cases where strep throat cause immune system to attack heart but it is very mild to be considered rheumatic fever?

Doubtful. If you have confirmed strep throat, the treatment of amoxicillin or azithromycin would protect from rheumatic fever, scarlet fever, etc. There are other conditions that can cause systemic symptoms of fever and shortness of breath (Lemierre's syndrome). If the process was a viral syndrome e.g mononucleosis (which can cause an exudative tonsillitis) the fatigue, sweats would persist. See a doctor. Read more...