The pain seems to be muscular because you are a software Engr & must be having a desk job working on comptr over long periods. although you are 24 yrs old & heart ailment is not likely, an ECG is indicated. I don't think this is a side effect of Antibiotic. A good clinical examination is required. I am a Sports Medicine specialist, Dr (Col) AK Mehta
Next Steps
To establish the diagnosis