I have always struggled with acne and it is definitely hormonal-related, which means there isn't a WHOLE lot you can do. But a dermatologist could prescribe RetinA which worked the best for me, although it takes a couple weeks to really work. Nothing will work immediately, in the sense that it takes 2 weeks for the pimples to form in your hair follicle, so all you can do for anything that's already shown up is try and speed the healing. But the RetinA works in the follicles to prevent future eruptions. Is the antibiotic your doctor gave you Benzyl Peroxide 10%? If not, I'd ask for that. And again, you have to use it regularly, not just when you have pimples.
I'd be wary of taking anything while pregnant (or using a hormone patch), so whatever you do make sure to clear it with the OB first! But a dermatologist will have a lot more experience with skin problems.
Try not to irritate the area, for example, even putting your chin in your hands while you are sitting (to lean on the table for example) can make it worse--just like you said about the football chin strap!
By the way, my derm said not to use scrubbing masks, as they irritate the skin. He said to use either Neutrogena or Purpose face soaps, because they rinse completely while other soaps leave a residue (there could be other brands but those 2 are good for sure)--and that's it, no toners etc.
Lastly, are you putting any kind of moisturizer on your skin? If so, I would limit that or make sure it's oil free, because very few of them are truly not going to clog the pores.
I never tried ProActiv, sounds like it's worth a shot! Can anyone tell what's the active ingredient in it? Many of the acne systems out there use salicylic acid and that never did a thing for me.
Hope that helps!
Lynn
Forgot to mention that SUN works wonders against acne! I know it's something we all try to limit on our skin, but in your case it might be worth leaving the sunscreen off that area and getting 15 min of sun on it (before it gets too cold!) Of course, when you're pregnant, the sun may cause darkening of the skin, so it's up to you whether you want to try it.