It is highly unlikely that you caught anything from an unprotected handjob. And, since you were wearing a condom, that has a very high probability of protecting you against any STDs although, it is very unlikely that the blowjob gave you any disease.... but,of course, it is not perfect.
That being said, receptive oral sex has a low probability of transmitting most types of STDs. This is especially true when protection is used....
So. What is the take home message?
From what you have posted it is unlikely that you caught any disease from this sexual encounter.
However, if you are really worried a quick visit to your doctor or a confidential STD clinic should be able to put your fears to rest.
Does this make sense to you?
I am happy to be able to help you today. If you would be so kind, please help me get credit for my efforts in answering your questions and press the excellent feedback button for this encounter. And, don’t forget, I work for tips. I would also be happy to continue to answer any more questions you have until we have resolved your concern.
Dr. Rick MD FACS