Hmmmmmm. Fisrt of all, I would tell my b/f that I was going to see the doctor alone. Period, end of subject. I would then tell the b/f that he will be welcome to accompany me when I say it is. He sounds controlling, which is not good and causes me concern. You state that you are scared to tell him about the spot on your vagina because he may think you cheated on him. If you've given him no reason to suspect your fidelity, then obviously trust is also an issue for him. Besides, you don't even know what it is yet. I'm sure your doctor, upon finding out you were pregnant, ran tests for all STDs and you were clear of them. I have no idea what this spot could be, but if your doctor was concerned, she wouldn't say "lets just keep our eye on it." She would agressively pursue a diagnosis.
I hate to say this, but if I were you, I'd be FAR more concerned about my boyfriends attitudes and insecurities than the spot. Sadly, in many cases, these behaviors can escalate into domestic violence. I know I am probably scaring you, but very soon, you will have a baby to protect and I want you to take a really hard look at your relationship with this guy.
Is there a trusted adult you can talk to about this? If so, I wish you would.
I wish you and your baby health and happiess..........and safety.
Peace
Greenlydia