Getting tested is the smartest thing you can do, not to incite panic or fear, but the symptoms you describe are indicative of a herpes simplex 2 outbreak. Herpes "flares" and cools, which is why it is such a contagious disease. He may have been with a partner that he didn't know had it.
Your boyfriend may have stayed protected during his time away from you- but wearing a condom is not 100% protection against herpes simply because Herpes effects the entire genital region- not just the shaft of the penis. If he had oral sex unprotected (as many people do) even if the person giving it had simplex one (oral herpes) he could have potentially contracted Herpes, and then passed it on to you.
Know two things;
Always look closely at the genitals of a person you are with- no matter how well you know them- during foreplay, with the lights on. If you see anything suspicious, get out of the situation. Even if they say "Oh it's just..." it's your health. If they want to be with you, they need to get tested.
Herpes is one of the most common sexually transmitted infections, affecting 1 in 4 people adults in america- scary stuff! If you do get a diagnosis of herpes there are several support groups and resources available to you out there.
Bumps can be from many different things, often not STD related, but you would have to see a Dr for a proper diagnosis. Testing alone might not tell you anything.