You didn't give this to your BF from this encounter. He received a diagnosis from his doctor.
Anyone who's sexually active should know their herpes status upfront. Consider this for you and your boyfriend - get tested so there are no worries, or precautions can be taken - going forward.
You need to look into your sexual history and see if you've ever had suspicious partners or instances of unprotected sex. If you have, you may want to get yourself tested. Request a type specific IgG blood test for HSV-1 and HSV-2.
Generally, if you did have Genital Herpes, your boyfriend would present with cold-sores, not necessarily viral throat ulcers. The symptoms he is experiencing may very well be unrelated to the oral sex encounter. Then again, if you are concerned, ask him to get blood test done as well.
The risk of contracting HSV from an oral encounter, whether giving or receiving is low risk.