Hi,
Welcome to the ehealthforum and I am glad to help you out. It is not possible to precisely confirm a diagnosis without physical examination but from the symptoms, this bump can be cysts or genital wart(caused by HPV infection).
Out of these only genital wart is sexually transmitted but it is not compulsory that he got it from you. The virus causing genital warts(HPV) can be transmitted in periods of asymptomatic shedding also and the virus may resurface at a later date. The only way with which you can confirm the diagnosis is by getting blood tests like antibody tests done for HPV. You should consult your doctor for the tests. Once the diagnosis is confirmed, treatment can be planned.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.