Boyfriends penis is sore after blowjob?

After I get my boyfriend a blowjob, he complains that his penis is sore. He explains to me it's not my fault and it's his first time receiving oral. It was also my first time giving oral. We're 17 and sooo new to everything. But I've done it 2 times after and it still gets sore to the point I can't even give him a handjob or he'll just be in pain. It goes away a few minutes later but, it just makes me feel so bad. Help?