You are right to be concerned. There are many kinds of liver problems (and some non-liver) that could cause your boyfriend's symptoms, but viral hepatitis is the most likely overall. Of the three kinds of viral hepatitis, types A and B are sexually transmitted; type C occasionally is sexually transmitted, but not usually. (The mixed messages about sexual transmission often concern hepatitis C, perhaps explaining the different advice you have heard.) If your BF has A or B, you need to be checked immediately, and if not already infected, you can be protected by being vaccinated and perhaps by receiving other treatment (immune globulin).
Bottom line: it is very important that you learn ASAP whether your BF has viral hepatitis and if so, which type. His doctor should have those answers already, or certainly within the next couple of days. Even if you can't get this information, see your own provider anyway. He or she can then contact your BF's doc to learn what is going on. Finally, if your own doc isn't up to speed on all this, contact your local health department for advice; or ask for referral to an infectious diseases or liver specialist.
Good luck-- HHH, MD
I definitely think you should go get tested, regardless of symptoms or timing.
HHH, MD