Hi,
The test only shows that you have / had an untreated case of infection by streptococcus bacteria. Have you taken the antibiotic treatment for this infection in the past?, since you say, you have it for two years and was the earlier medication something different from penicillin ? In any case, it is important to bring down the ASO value by medication as continuing infection can lead to some complications. You can get more details from the following link :
http://labtestsonline.org/understanding/analytes/aso/tab/tab/sample
You do not have to worry, every one gets diseases once in a while, so just follow the doctor's advice.
Solace